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Heart Failure and Hip Fracture Repair
As the population ages, hip fractures and heart failure increase in prevalence.1, 2 Heart failure prevalence is also increasing in hospitalized patients.3 Indeed, hospitalizations involving heart failure as an active issue tripled in the last 30 years.4 Heart failure has been associated with an increased risk for hip fracture,5, 6 and previous studies report a 6%20% prevalence of preoperative heart failure in hip fracture patients.710 While exacerbation of heart failure increases the mortality risk in patients admitted for hip fractures,8 the incidence of new heart failure, as well as the preoperative factors that predict postoperative heart failure in this patient population remain unclear.
American College of Cardiology/American Heart Association (ACC/AHA) perioperative guidelines identify orthopedic surgeries, including hip fracture repair, as intermediate risk procedures.11 Compared to other intermediate risk operations, however, postoperative outcomes following hip fracture repair differ significantly.1216 Overall mortality in hip fracture patients has been reported at 29% at one year,8 with the excess mortality from hip fracture alone at nearly 20%.10, 13 However, the exact factors that contribute to this excess mortality, particularly with regard to heart failure, remain unclear.
To examine the preoperative prevalence, subsequent incidence, and predictors of heart failure in patients undergoing hip fracture repair operations, this study used an established, population‐based database to compare the postoperative consequences in hip fracture repair patients with and without preexisting heart failure. We hypothesized that preoperative heart failure worsens postoperative outcomes in hip fracture patients.
METHODS
Case Ascertainment
Following approval by the Institutional Review Boards of Mayo Clinic and the Olmsted Medical Center, we used the Rochester Epidemiology Project (REP) to identify the patients for this study. The REP is a population‐based medical records linkage system that records all diagnoses, surgical procedures, laboratory data, and death information from hospital, emergency room, outpatient, and nursing home care in the community.17
All Olmsted County, Minnesota, residents who sustained a hip fracture and underwent surgical repair from 1988 through 2002 were evaluated. Patients with more than one hip fracture during the study period (96 occurrences) were censored from the data analysis at the time of the subsequent hip fracture and then included as new cases. The complete enumeration of hip fracture episodes managed in the three Olmsted County hospital facilities (Mayo Clinic's Saint Mary's and Rochester Methodist Hospitals, and the Olmsted Medical Center Hospital) occurred in three phases: First, all hospitalizations with the surgical procedure (International Statistical Classification of Diseases, 9th Revision [ICD‐9]) codes 79.15 (reduction, fracture, femur, closed with internal fixation), 79.25 (reduction, fracture, femur, open, without internal fixation), 79.35 (reduction, fracture, femur, open with internal fixation), 79.95 (operation, unspecified bone injury, femur), 80.05 (arthrotomy for removal of hip prosthesis), 80.15 (arthrotomy, other, hip), 80.95 (excision, hip joint), 81.21 (arthrodesis, hip), 81.40 (repair hip, not elsewhere classified), 81.51 (total hip replacement), 81.52 (partial hip replacement), and 81.53 (revision hip replacement) were identified. Second, through review of the original inpatient and outpatient medical records, we confirmed that a fracture was associated with the index hospitalization. Finally, radiology reports of each index hospitalization verified the presence and exact anatomical location of each fracture. Of those with fractures on admission x‐rays, only patients with a proximal femur (femoral neck or intertrochanteric) fracture as the primary indication for the surgery were included in the study. Surgical report or radiographic evidence of hip fracture was available for all patients. Secondary fractures due to a specific pathological lesion (eg, malignancy) or high‐energy trauma (by convention, motor vehicle accidents or falls from significant heights) were excluded. Only patients who had provided an authorization to review their medical records for research were ultimately included in the study cohort.18 Medical records were search manually, if indicated.
Criteria for Heart Failure and Death
Preoperative heart failure was based on clinical documentation of heart failure in a patient's medical record prior to the time of the hip fracture repair. Postoperative heart failure, including acute exacerbations, was defined according to Framingham criteria.19 Framingham criteria included clinical evidence of increased central venous pressure, pulmonary edema, an S3 gallop, radiographic pulmonary edema, and response to diuresis. Heart failure was not graded on clinical severity (ie, New York Heart Association classification). We did not distinguish between systolic and diastolic heart failure. Mortality was defined as death from any cause within the first year following hip fracture repair. Deaths were identified either through REP resources or the National Death Index.
Statistical Methods
Continuous variables are presented as mean standard deviation and categorical variables as number (percent). Two‐sample t tests or Wilcoxon rank sum tests were used to test for significant differences in continuous variables. Chi‐square or Fisher's exact tests were used for categorical variables. Rates of postoperative outcomes were calculated using the KaplanMeier method for the overall group and for those with and without preoperative heart failure. A landmark survival curve was used to evaluate postoperative mortality among patients who experienced heart failure in the first seven postoperative days versus those who did not. Patients who died or underwent another hip operation within the first seven postoperative days were excluded from this analysis. Univariate Cox proportional hazards models were used to evaluate the predictors of postoperative heart failure and mortality. Patients who died or experienced a second hip surgery within one year of their first were censored at that time. Any subsequent hip fracture repair was treated as a new case. To account for the inclusion of multiple hip fracture repairs for a given patient, the Cox proportional hazards model included a robust variance estimator. This provided an accurate calculation of the standard error in the presence of within‐subject correlation.20 Statistical tests were two‐sided, and P values were considered significant if less than 0.05. Statistical analyses were performed using SAS (version 9.1.3, SAS Institute, Cary, NC).
RESULTS
From among 1327 potential hip fracture repairs, we excluded 115 cases involving multiple injuries or operations (19), pathological fractures (20), in‐hospital fractures (3), or an operation >72 hours after the initial fracture (5). Three patients under 65 years of age were also excluded, as were cases with missing information (9) or cases managed nonoperatively (56). The final analysis included 1212 surgical cases in 1116 subjects. No subjects were lost to surveillance for 1 year following their hip fracture repair.
Table 1 summarizes the baseline characteristics of the study population. The overall prevalence of preoperative heart failure was 27.0% (327 of 1212). Those with preoperative heart failure were older, heavier, more likely male and white, and less likely to live independently preoperatively. They were also more likely to suffer from preexisting cardiovascular comorbidities.
All (N = 1,212) | HF (N = 327) | No HF (N = 885) | P Value* | |
---|---|---|---|---|
| ||||
Demographics | ||||
Mean age (years) (SD) | 84.2 (7.44) | 85.5 (6.54) | 83.7 (7.70) | 0.00101 |
Male gender | 237 (19.6) | 76 (23.2) | 161 (18.2) | 0.04912 |
Mean BMI (kg/m2) (SD) | 23.3 (4.97) | 24.1 (5.68) | 23.0 (4.65) | 0.01231 |
White | 1,204 (99.3) | 322 (98.5) | 882 (99.7) | 0.03713 |
Preoperative living situation | ||||
Nursing facility | 468 (38.6) | 144 (44) | 324 (36.6) | 0.01842 |
Home | 744 (61.4) | 183 (56) | 561 (63.4) | 0.05192 |
Preoperative ambulatory status | ||||
Dependent | 149 (12.3) | 50 (15.3) | 99 (11.2) | |
Independent | 1,061 (87.7) | 276 (84.7) | 785 (88.8) | |
Medical history | ||||
Hypertension | 705 (58.2) | 226 (69.1) | 479 (54.1) | <0.00012 |
Diabetes mellitus | 143 (11.8) | 63 (19.3) | 80 (9) | <0.00012 |
Cerebrovascular disease | 331 (27.3) | 129 (39.4) | 202 (22.8) | <0.00012 |
Peripheral vascular disease | 195 (16.1) | 80 (24.5) | 115 (13) | <0.00012 |
Coronary artery disease | 464 (38.3) | 237 (72.5) | 227 (25.6) | <0.00012 |
Atrial fibrillation/flutter | 254 (21) | 133 (40.7) | 121 (13.7) | <0.00012 |
Complete heart block | 18 (1.5) | 9 (2.8) | 9 (1) | 0.03373 |
Pacer at time of admission | 32 (2.6) | 16 (4.9) | 16 (1.8) | 0.00292 |
Chronic obstructive pulmonary disease | 196 (16.2) | 78 (23.9) | 118 (13.3) | <0.00012 |
Liver disease | 15 (1.2) | 7 (2.1) | 8 (0.9) | 0.13753 |
Chronic renal insufficiency | 131 (10.8) | 61 (18.7) | 70 (7.9) | <0.00012 |
Mean length of hospitalization (days) (SD) | 10.0 (7.57) | 11.1 (8.82) | 9.6 (7.01) | 0.00101 |
Discharge disposition | 0.00192 | |||
Home | 150 (12.4) | 26 (8.0) | 124 (14.0) | |
Skilled nursing facility | 1,004 (82.9) | 278 (85.0) | 726 (82.1) | |
Dead | 57 (4.7) | 23 (7.0) | 34 (3.9) |
Table 1 also summarizes the main outcome characteristics of the study population. Those with preoperative heart failure had longer mean lengths of stay (LOS), were more often discharged to a skilled facility, and demonstrated higher inpatient mortality rates.
Table 2 summarizes the outcomes associated with preoperative heart failure. The overall rate of postoperative heart failure was 6.7% within 7 postoperative days and 21.3% within 1 postoperative year. Postoperative heart failure was significantly more common among those with preoperative heart failure (hazard ratio [HR], 3.0; 95% confidence interval [CI], 2.3 to 3.9; P < 0.001). Among those without preoperative heart failure, rates of postoperative incident heart failure were 4.8% at 7 days and 15.0% at 1 year. Compared to patients without preoperative heart failure, those with preoperative heart failure demonstrated higher one year mortality rates and higher rates of postoperative heart failure at 7 days and 1 year.
Preoperative Heart Failure (Subjects) | |||||
---|---|---|---|---|---|
Outcome | All (N = 1212) | No (N = 885) | Yes (N = 327) | Risk ratio* (95% CI) | P Value |
| |||||
Heart failure exacerbation within seven postoperative days | 6.7% (5.4, 8.3) | 4.8% (3.5, 6.5) | 12.1% (8.7, 16.2) | 2.72 (1.72, 4.31) | <0.0001 |
One‐year postoperative heart failure exacerbation | 21.3% (18.8, 23.7) | 15.0% (12.5, 17.4) | 39.3% (33.3, 44.9) | 3.00 (2.32, 3.87) | <0.0001 |
One‐year postoperative mortality | 24.5% (22.0, 26.9) | 19.8% (17.1, 22.4) | 37.2% (31.6, 42.3) | 2.11 (1.67, 2.67) | <0.0001 |
One‐year postoperative mortality or heart failure exacerbation | 36.5% (33.7, 39.2) | 29.7% (26.6, 32.6) | 55.0% (49.3, 60.2) | 2.28 (1.88, 2.76) | <0.0001 |
Figure 1 displays the outcomes to 1 year of surveillance. Rates of postoperative heart failure and postoperative mortality were consistently higher among those with, versus without, preoperative heart failure. Figure 2 displays similar data stratified by gender. Postoperative heart failure rates did not differ significantly between genders (HR, 1.0; 95% CI, 0.8 to 1.4), but postoperative mortality rates were significantly higher among males than females (HR, 1.9; 95% CI, 1.5 to 2.5; P < 0.001).
Figure 3 displays survival rates to 1 year based on the occurrence of incident or recurrent heart failure within the first 7 postoperative days. Survival rates were lowest among patients with recurrent heart failure in the first 7 postoperative days and highest among those with no preoperative or postoperative heart failure. Subjects with incident heart failure in the first postoperative week, and those with preoperative heart failure who did not suffer a recurrence, demonstrated intermediate survival rates (P < 0.001 for trend across all four groups).
DISCUSSION
This population‐based study found that heart failure represents a highly prevalent condition in elderly patients undergoing hip fracture repairs. It demonstrates that those with preoperative heart failure typically suffer from more cardiovascular comorbidities and carry a higher risk of postoperative heart failure and postoperative mortality.
While many studies have focused on the epidemiology of hip fractures,21 population‐based data on cardiac complications following hip fracture repair are significantly less common. The ACC/AHA preoperative cardiac evaluation guidelines classify orthopedic procedures, including hip fracture repair, as intermediate risk.11 Consequently, some may assume that all orthopedic patients will have a mortality rate less than 5%. Indeed, the 30‐day postoperative mortality rate published from our institution's Total Joint Registry was 0.6% following elective total hip arthroplasty.22 However, the present study demonstrates that current ACC/AHA preoperative cardiac evaluation guidelines may not apply to the population of frail patients undergoing hip fracture repair. Particularly among those who experience new heart failure within the first seven days following surgery, outcomes are substantially worse than the ACC/AHA perioperative guidelines may suggest.11
Preoperative heart failure has been associated with adverse risk for postoperative mortality after hip fracture.9, 10, 12 However, these studies did not report heart failure as a complication of hip fracture repair. A prospective cohort study of 2448 hip fracture patients at an academic hospital in Great Britain found a 5% rate of inpatient heart failure as a postoperative complication.23 The hazard ratio for one‐year mortality was 11.3 with postoperative heart failure.23 However, the British study did not distinguish heart failure from other cardiovascular diseases as a preoperative comorbidity or stratify the risk for postoperative mortality by preoperative heart failure status.23 Our findings add to previous literature by measuring heart failure as a specific complication of hip fracture repair and examining the association of preoperative heart failure with postoperative heart failure and mortality.
Length of stay after hip fracture repair varies in the literature, but previous work has not clearly associated heart failure with length of hospitalization in the setting of hip fracture repair.24, 25 Our study found a significantly higher mean length of stay among those with preoperative heart failure. This adds to previous work by delineating an association between heart failure and increased length of stay after hip fracture repair.
We found a higher rate of postoperative mortality among men compared to women. Rates of postoperative heart failure, however, were more similar (Figure 2). Previous studies have found a consistently higher mortality rate among men versus women after hip fracture.9, 23, 2529 Possible explanations for these findings include the overall increased burden of cardiovascular disease among men, lower treatment rates of osteoporosis in men,30 and increased susceptibility to other postoperative complications, such as infection.25
The findings of this study carry important clinical implications for the perioperative care of hip fracture patients with, or at risk for, heart failure. They suggest that current risk stratification guidelines classifying orthopedic operations as intermediate risk procedures do not reflect the high risk for morbidity that hip fracture patients face.11 The association of heart failure with adverse outcomes implies the need for heightened surveillance in the perioperative period, particularly with regard to volume status and medication reconciliation. Hip fracture patients and their families must be counseled about the ramifications of perioperative heart failure, including higher rates of postoperative heart failure, longer hospitalizations, and ultimate mortality.
This research carries several limitations and remains subject to biases inherent in retrospective cohort studies. The reported effects of heart failure on outcomes after hip fracture repair may be due to confounding from age, functional status, and other comorbidities. We attempted to minimize sampling bias through complete enumeration of hip fracture surgeries among Olmsted County residents. Completeness of follow‐up (100% at one year) was possible given the availability of documentation of all inpatient and outpatient medical care in the community.17 We used objectively defined outcomes to minimize measurement bias. Applicability to a more diverse population may be limited because >95% of the research population was from a single, predominantly white community. However, prior studies have documented that hip fracture incidence rates31 and socioeconomic factors17 in Olmsted County are similar to those for other white residents of the United States. Heart failure rates were determined clinically according to the Framingham criteria. However, the Framingham criteria may inappropriately diagnose individuals with heart failure32 and falsely elevate the prevalence of heart failure as a preoperative comorbidity or postoperative complication.
The statistical analysis included patients counted multiple times if they underwent subsequent hip fracture repair during the study period. Including these patients may inaccurately inflate event rates or contribute to incorrect estimates of standard error. However, we felt it was appropriate to include recurrent hip fracture repair cases in the analysis because they represent a clinically distinct patient from both a medical and functional perspective. We used a robust variance estimator in the Cox proportional hazards models to provide an accurate calculation of the standard error given the possibility for correlation within subjects.20 Finally, the proportion of these patients was low (94 of 1116 unique patients; 8.4%).
Future work must involve further risk stratification and therapeutic interventions in perioperative hip fracture patients. A more robust analysis of heart failure, with differentiation between systolic and diastolic dysfunction, may facilitate risk stratification. Assessment of compliance with standard preoperative heart failure medications and the impact of heightened clinical vigilance may enlighten means to improve postoperative outcomes. Studies on risk stratification and therapeutic interventions may then inform policy regarding length of stay and reimbursement in hip fracture patients.
CONCLUSION
In summary, our population‐based findings reveal that heart failure represents a prevalent and serious comorbidity in patients undergoing hip fracture repair. Clinicians caring for perioperative hip fracture patients must pay particular attention to risk for, and implications of, new or recurrent heart failure.
Acknowledgements
The authors thank Donna K. Lawson, LPN, Kathy Wolfert, and Cherie Dolliver for their assistance in data collection and management.
- Epidemiology of hip fractures: Implications of the exponential increase with age.Bone.1996;18(3 suppl):121S–125S. .
- Trends in length of stay and short‐term outcomes among Medicare patients hospitalized for heart failure, 1993–2006.JAMA.2010;303(21):2141–2147. , , , et al.
- The expanding national burden of heart failure in the United States: The influence of heart failure in women.Am Heart J.2004;147(1):74–78. , , , , .
- Heart failure‐related hospitalization in the U.S., 1979 to 2004.J Am Coll Cardiol.2008;52(6):428–434. , , , .
- Heart failure is a risk factor for orthopedic fracture: A population‐based analysis of 16,294 patients.Circulation.2008;118(19):1946–1952. , , , , .
- Cardiovascular diseases and risk of hip fracture.JAMA.2009;302(15):1666–1673. , , , et al.
- Effectiveness of hospitalist involvement in hip fracture management questioned.South Med J.2007;100(9):912–913. , , , .
- Effects of a hospitalist care model on mortality of elderly patients with hip fractures.J Hosp Med.2007;2(4):219–225. , , , et al.
- Excess mortality in men compared with women following a hip fracture. National analysis of comedications, comorbidity and survival.Age Ageing.2010;39(2):203–209. , , , .
- Increased mortality in patients with a hip fracture—Effect of pre‐morbid conditions and post‐fracture complications.Osteoporos Int.2007;18(12):1583–1593. , , .
- ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: Executive summary: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery): Developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, and Society for Vascular Surgery.J Am Coll Cardiol.2007;50(17):1707–1732. , , , et al.
- Excess mortality following hip fracture: The role of underlying health status.Osteoporos Int.2007;18(11):1463–1472. , , , , .
- Time trends of mortality after first hip fractures.Osteoporos Int.2007;18(6):721–732. .
- Mortality and locomotion 6 months after hospitalization for hip fracture: Risk factors and risk‐adjusted hospital outcomes.JAMA.2001;285(21):2736–2742. , , , et al.
- Factors associated with mortality after hip fracture.Osteoporos Int.2000;11(3):228–232. , , , .
- Hip fractures among the elderly: Factors associated with in‐hospital mortality.Am J Epidemiol.1991;134(10):1128–1137. , , , , , .
- History of the Rochester Epidemiology Project.Mayo Clin Proc.1996;71(3):266–274. .
- The threat to medical‐records research.N Engl J Med.1997;337(20):1466–1470. .
- The natural history of congestive heart failure: The Framingham Study.N Engl J Med.1971;285(26):1441–1446. , , , .
- The robust inference for the Cox proportional hazards model.J Am Stat Assoc.1989;84(408):1074–1078. , .
- Hip fracture epidemiological trends, outcomes, and risk factors, 1970–2009.Int J Gen Med.2010;3:1–17. .
- Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty.Anesthesiology.2002;96(5):1140–1146. , , , , , .
- Effect of comorbidities and postoperative complications on mortality after hip fracture in elderly people: Prospective observational cohort study.BMJ.2005;331(7529):1374–1376. , , , .
- The aftermath of hip fracture: Discharge placement, functional status change, and mortality.Am J Epidemiol.2009;170(10):1290–1299. , , , et al.
- Gender differences in mortality after hip fracture: The role of infection.J Bone Miner Res.2003;18(12):2231–2237. , , , , , .
- Mortality after all major types of osteoporotic fracture in men and women: An observational study.Lancet.1999;353(9156):878–882. , , , , .
- Adjusted mortality after hip fracture: From the Cardiovascular Health Study.J Am Geriatr Soc.2006;54(12):1885–1891. , , .
- Meta‐analysis: Excess mortality after hip fracture among older women and men.Ann Intern Med.2010;152(6):380–390. , , , et al.
- Predictors of hip fractures in elderly men.J Bone Miner Res.1995;10(12):1900–1907. , , , .
- Population‐based fracture risk assessment and osteoporosis treatment disparities by race and gender.J Gen Intern Med.2009;24(8):956–962. , , , et al.
- Long‐term trends in hip fracture prevalence: The influence of hip fracture incidence and survival.Osteoporos Int.1998;8(1):68–74. , , .
- diagnostic accuracy of clinical criteria for identifying systolic and diastolic heart failure: Cross‐sectional study.J Eval Clin Pract.2009;15(1):55–61. , , , , , .
As the population ages, hip fractures and heart failure increase in prevalence.1, 2 Heart failure prevalence is also increasing in hospitalized patients.3 Indeed, hospitalizations involving heart failure as an active issue tripled in the last 30 years.4 Heart failure has been associated with an increased risk for hip fracture,5, 6 and previous studies report a 6%20% prevalence of preoperative heart failure in hip fracture patients.710 While exacerbation of heart failure increases the mortality risk in patients admitted for hip fractures,8 the incidence of new heart failure, as well as the preoperative factors that predict postoperative heart failure in this patient population remain unclear.
American College of Cardiology/American Heart Association (ACC/AHA) perioperative guidelines identify orthopedic surgeries, including hip fracture repair, as intermediate risk procedures.11 Compared to other intermediate risk operations, however, postoperative outcomes following hip fracture repair differ significantly.1216 Overall mortality in hip fracture patients has been reported at 29% at one year,8 with the excess mortality from hip fracture alone at nearly 20%.10, 13 However, the exact factors that contribute to this excess mortality, particularly with regard to heart failure, remain unclear.
To examine the preoperative prevalence, subsequent incidence, and predictors of heart failure in patients undergoing hip fracture repair operations, this study used an established, population‐based database to compare the postoperative consequences in hip fracture repair patients with and without preexisting heart failure. We hypothesized that preoperative heart failure worsens postoperative outcomes in hip fracture patients.
METHODS
Case Ascertainment
Following approval by the Institutional Review Boards of Mayo Clinic and the Olmsted Medical Center, we used the Rochester Epidemiology Project (REP) to identify the patients for this study. The REP is a population‐based medical records linkage system that records all diagnoses, surgical procedures, laboratory data, and death information from hospital, emergency room, outpatient, and nursing home care in the community.17
All Olmsted County, Minnesota, residents who sustained a hip fracture and underwent surgical repair from 1988 through 2002 were evaluated. Patients with more than one hip fracture during the study period (96 occurrences) were censored from the data analysis at the time of the subsequent hip fracture and then included as new cases. The complete enumeration of hip fracture episodes managed in the three Olmsted County hospital facilities (Mayo Clinic's Saint Mary's and Rochester Methodist Hospitals, and the Olmsted Medical Center Hospital) occurred in three phases: First, all hospitalizations with the surgical procedure (International Statistical Classification of Diseases, 9th Revision [ICD‐9]) codes 79.15 (reduction, fracture, femur, closed with internal fixation), 79.25 (reduction, fracture, femur, open, without internal fixation), 79.35 (reduction, fracture, femur, open with internal fixation), 79.95 (operation, unspecified bone injury, femur), 80.05 (arthrotomy for removal of hip prosthesis), 80.15 (arthrotomy, other, hip), 80.95 (excision, hip joint), 81.21 (arthrodesis, hip), 81.40 (repair hip, not elsewhere classified), 81.51 (total hip replacement), 81.52 (partial hip replacement), and 81.53 (revision hip replacement) were identified. Second, through review of the original inpatient and outpatient medical records, we confirmed that a fracture was associated with the index hospitalization. Finally, radiology reports of each index hospitalization verified the presence and exact anatomical location of each fracture. Of those with fractures on admission x‐rays, only patients with a proximal femur (femoral neck or intertrochanteric) fracture as the primary indication for the surgery were included in the study. Surgical report or radiographic evidence of hip fracture was available for all patients. Secondary fractures due to a specific pathological lesion (eg, malignancy) or high‐energy trauma (by convention, motor vehicle accidents or falls from significant heights) were excluded. Only patients who had provided an authorization to review their medical records for research were ultimately included in the study cohort.18 Medical records were search manually, if indicated.
Criteria for Heart Failure and Death
Preoperative heart failure was based on clinical documentation of heart failure in a patient's medical record prior to the time of the hip fracture repair. Postoperative heart failure, including acute exacerbations, was defined according to Framingham criteria.19 Framingham criteria included clinical evidence of increased central venous pressure, pulmonary edema, an S3 gallop, radiographic pulmonary edema, and response to diuresis. Heart failure was not graded on clinical severity (ie, New York Heart Association classification). We did not distinguish between systolic and diastolic heart failure. Mortality was defined as death from any cause within the first year following hip fracture repair. Deaths were identified either through REP resources or the National Death Index.
Statistical Methods
Continuous variables are presented as mean standard deviation and categorical variables as number (percent). Two‐sample t tests or Wilcoxon rank sum tests were used to test for significant differences in continuous variables. Chi‐square or Fisher's exact tests were used for categorical variables. Rates of postoperative outcomes were calculated using the KaplanMeier method for the overall group and for those with and without preoperative heart failure. A landmark survival curve was used to evaluate postoperative mortality among patients who experienced heart failure in the first seven postoperative days versus those who did not. Patients who died or underwent another hip operation within the first seven postoperative days were excluded from this analysis. Univariate Cox proportional hazards models were used to evaluate the predictors of postoperative heart failure and mortality. Patients who died or experienced a second hip surgery within one year of their first were censored at that time. Any subsequent hip fracture repair was treated as a new case. To account for the inclusion of multiple hip fracture repairs for a given patient, the Cox proportional hazards model included a robust variance estimator. This provided an accurate calculation of the standard error in the presence of within‐subject correlation.20 Statistical tests were two‐sided, and P values were considered significant if less than 0.05. Statistical analyses were performed using SAS (version 9.1.3, SAS Institute, Cary, NC).
RESULTS
From among 1327 potential hip fracture repairs, we excluded 115 cases involving multiple injuries or operations (19), pathological fractures (20), in‐hospital fractures (3), or an operation >72 hours after the initial fracture (5). Three patients under 65 years of age were also excluded, as were cases with missing information (9) or cases managed nonoperatively (56). The final analysis included 1212 surgical cases in 1116 subjects. No subjects were lost to surveillance for 1 year following their hip fracture repair.
Table 1 summarizes the baseline characteristics of the study population. The overall prevalence of preoperative heart failure was 27.0% (327 of 1212). Those with preoperative heart failure were older, heavier, more likely male and white, and less likely to live independently preoperatively. They were also more likely to suffer from preexisting cardiovascular comorbidities.
All (N = 1,212) | HF (N = 327) | No HF (N = 885) | P Value* | |
---|---|---|---|---|
| ||||
Demographics | ||||
Mean age (years) (SD) | 84.2 (7.44) | 85.5 (6.54) | 83.7 (7.70) | 0.00101 |
Male gender | 237 (19.6) | 76 (23.2) | 161 (18.2) | 0.04912 |
Mean BMI (kg/m2) (SD) | 23.3 (4.97) | 24.1 (5.68) | 23.0 (4.65) | 0.01231 |
White | 1,204 (99.3) | 322 (98.5) | 882 (99.7) | 0.03713 |
Preoperative living situation | ||||
Nursing facility | 468 (38.6) | 144 (44) | 324 (36.6) | 0.01842 |
Home | 744 (61.4) | 183 (56) | 561 (63.4) | 0.05192 |
Preoperative ambulatory status | ||||
Dependent | 149 (12.3) | 50 (15.3) | 99 (11.2) | |
Independent | 1,061 (87.7) | 276 (84.7) | 785 (88.8) | |
Medical history | ||||
Hypertension | 705 (58.2) | 226 (69.1) | 479 (54.1) | <0.00012 |
Diabetes mellitus | 143 (11.8) | 63 (19.3) | 80 (9) | <0.00012 |
Cerebrovascular disease | 331 (27.3) | 129 (39.4) | 202 (22.8) | <0.00012 |
Peripheral vascular disease | 195 (16.1) | 80 (24.5) | 115 (13) | <0.00012 |
Coronary artery disease | 464 (38.3) | 237 (72.5) | 227 (25.6) | <0.00012 |
Atrial fibrillation/flutter | 254 (21) | 133 (40.7) | 121 (13.7) | <0.00012 |
Complete heart block | 18 (1.5) | 9 (2.8) | 9 (1) | 0.03373 |
Pacer at time of admission | 32 (2.6) | 16 (4.9) | 16 (1.8) | 0.00292 |
Chronic obstructive pulmonary disease | 196 (16.2) | 78 (23.9) | 118 (13.3) | <0.00012 |
Liver disease | 15 (1.2) | 7 (2.1) | 8 (0.9) | 0.13753 |
Chronic renal insufficiency | 131 (10.8) | 61 (18.7) | 70 (7.9) | <0.00012 |
Mean length of hospitalization (days) (SD) | 10.0 (7.57) | 11.1 (8.82) | 9.6 (7.01) | 0.00101 |
Discharge disposition | 0.00192 | |||
Home | 150 (12.4) | 26 (8.0) | 124 (14.0) | |
Skilled nursing facility | 1,004 (82.9) | 278 (85.0) | 726 (82.1) | |
Dead | 57 (4.7) | 23 (7.0) | 34 (3.9) |
Table 1 also summarizes the main outcome characteristics of the study population. Those with preoperative heart failure had longer mean lengths of stay (LOS), were more often discharged to a skilled facility, and demonstrated higher inpatient mortality rates.
Table 2 summarizes the outcomes associated with preoperative heart failure. The overall rate of postoperative heart failure was 6.7% within 7 postoperative days and 21.3% within 1 postoperative year. Postoperative heart failure was significantly more common among those with preoperative heart failure (hazard ratio [HR], 3.0; 95% confidence interval [CI], 2.3 to 3.9; P < 0.001). Among those without preoperative heart failure, rates of postoperative incident heart failure were 4.8% at 7 days and 15.0% at 1 year. Compared to patients without preoperative heart failure, those with preoperative heart failure demonstrated higher one year mortality rates and higher rates of postoperative heart failure at 7 days and 1 year.
Preoperative Heart Failure (Subjects) | |||||
---|---|---|---|---|---|
Outcome | All (N = 1212) | No (N = 885) | Yes (N = 327) | Risk ratio* (95% CI) | P Value |
| |||||
Heart failure exacerbation within seven postoperative days | 6.7% (5.4, 8.3) | 4.8% (3.5, 6.5) | 12.1% (8.7, 16.2) | 2.72 (1.72, 4.31) | <0.0001 |
One‐year postoperative heart failure exacerbation | 21.3% (18.8, 23.7) | 15.0% (12.5, 17.4) | 39.3% (33.3, 44.9) | 3.00 (2.32, 3.87) | <0.0001 |
One‐year postoperative mortality | 24.5% (22.0, 26.9) | 19.8% (17.1, 22.4) | 37.2% (31.6, 42.3) | 2.11 (1.67, 2.67) | <0.0001 |
One‐year postoperative mortality or heart failure exacerbation | 36.5% (33.7, 39.2) | 29.7% (26.6, 32.6) | 55.0% (49.3, 60.2) | 2.28 (1.88, 2.76) | <0.0001 |
Figure 1 displays the outcomes to 1 year of surveillance. Rates of postoperative heart failure and postoperative mortality were consistently higher among those with, versus without, preoperative heart failure. Figure 2 displays similar data stratified by gender. Postoperative heart failure rates did not differ significantly between genders (HR, 1.0; 95% CI, 0.8 to 1.4), but postoperative mortality rates were significantly higher among males than females (HR, 1.9; 95% CI, 1.5 to 2.5; P < 0.001).
Figure 3 displays survival rates to 1 year based on the occurrence of incident or recurrent heart failure within the first 7 postoperative days. Survival rates were lowest among patients with recurrent heart failure in the first 7 postoperative days and highest among those with no preoperative or postoperative heart failure. Subjects with incident heart failure in the first postoperative week, and those with preoperative heart failure who did not suffer a recurrence, demonstrated intermediate survival rates (P < 0.001 for trend across all four groups).
DISCUSSION
This population‐based study found that heart failure represents a highly prevalent condition in elderly patients undergoing hip fracture repairs. It demonstrates that those with preoperative heart failure typically suffer from more cardiovascular comorbidities and carry a higher risk of postoperative heart failure and postoperative mortality.
While many studies have focused on the epidemiology of hip fractures,21 population‐based data on cardiac complications following hip fracture repair are significantly less common. The ACC/AHA preoperative cardiac evaluation guidelines classify orthopedic procedures, including hip fracture repair, as intermediate risk.11 Consequently, some may assume that all orthopedic patients will have a mortality rate less than 5%. Indeed, the 30‐day postoperative mortality rate published from our institution's Total Joint Registry was 0.6% following elective total hip arthroplasty.22 However, the present study demonstrates that current ACC/AHA preoperative cardiac evaluation guidelines may not apply to the population of frail patients undergoing hip fracture repair. Particularly among those who experience new heart failure within the first seven days following surgery, outcomes are substantially worse than the ACC/AHA perioperative guidelines may suggest.11
Preoperative heart failure has been associated with adverse risk for postoperative mortality after hip fracture.9, 10, 12 However, these studies did not report heart failure as a complication of hip fracture repair. A prospective cohort study of 2448 hip fracture patients at an academic hospital in Great Britain found a 5% rate of inpatient heart failure as a postoperative complication.23 The hazard ratio for one‐year mortality was 11.3 with postoperative heart failure.23 However, the British study did not distinguish heart failure from other cardiovascular diseases as a preoperative comorbidity or stratify the risk for postoperative mortality by preoperative heart failure status.23 Our findings add to previous literature by measuring heart failure as a specific complication of hip fracture repair and examining the association of preoperative heart failure with postoperative heart failure and mortality.
Length of stay after hip fracture repair varies in the literature, but previous work has not clearly associated heart failure with length of hospitalization in the setting of hip fracture repair.24, 25 Our study found a significantly higher mean length of stay among those with preoperative heart failure. This adds to previous work by delineating an association between heart failure and increased length of stay after hip fracture repair.
We found a higher rate of postoperative mortality among men compared to women. Rates of postoperative heart failure, however, were more similar (Figure 2). Previous studies have found a consistently higher mortality rate among men versus women after hip fracture.9, 23, 2529 Possible explanations for these findings include the overall increased burden of cardiovascular disease among men, lower treatment rates of osteoporosis in men,30 and increased susceptibility to other postoperative complications, such as infection.25
The findings of this study carry important clinical implications for the perioperative care of hip fracture patients with, or at risk for, heart failure. They suggest that current risk stratification guidelines classifying orthopedic operations as intermediate risk procedures do not reflect the high risk for morbidity that hip fracture patients face.11 The association of heart failure with adverse outcomes implies the need for heightened surveillance in the perioperative period, particularly with regard to volume status and medication reconciliation. Hip fracture patients and their families must be counseled about the ramifications of perioperative heart failure, including higher rates of postoperative heart failure, longer hospitalizations, and ultimate mortality.
This research carries several limitations and remains subject to biases inherent in retrospective cohort studies. The reported effects of heart failure on outcomes after hip fracture repair may be due to confounding from age, functional status, and other comorbidities. We attempted to minimize sampling bias through complete enumeration of hip fracture surgeries among Olmsted County residents. Completeness of follow‐up (100% at one year) was possible given the availability of documentation of all inpatient and outpatient medical care in the community.17 We used objectively defined outcomes to minimize measurement bias. Applicability to a more diverse population may be limited because >95% of the research population was from a single, predominantly white community. However, prior studies have documented that hip fracture incidence rates31 and socioeconomic factors17 in Olmsted County are similar to those for other white residents of the United States. Heart failure rates were determined clinically according to the Framingham criteria. However, the Framingham criteria may inappropriately diagnose individuals with heart failure32 and falsely elevate the prevalence of heart failure as a preoperative comorbidity or postoperative complication.
The statistical analysis included patients counted multiple times if they underwent subsequent hip fracture repair during the study period. Including these patients may inaccurately inflate event rates or contribute to incorrect estimates of standard error. However, we felt it was appropriate to include recurrent hip fracture repair cases in the analysis because they represent a clinically distinct patient from both a medical and functional perspective. We used a robust variance estimator in the Cox proportional hazards models to provide an accurate calculation of the standard error given the possibility for correlation within subjects.20 Finally, the proportion of these patients was low (94 of 1116 unique patients; 8.4%).
Future work must involve further risk stratification and therapeutic interventions in perioperative hip fracture patients. A more robust analysis of heart failure, with differentiation between systolic and diastolic dysfunction, may facilitate risk stratification. Assessment of compliance with standard preoperative heart failure medications and the impact of heightened clinical vigilance may enlighten means to improve postoperative outcomes. Studies on risk stratification and therapeutic interventions may then inform policy regarding length of stay and reimbursement in hip fracture patients.
CONCLUSION
In summary, our population‐based findings reveal that heart failure represents a prevalent and serious comorbidity in patients undergoing hip fracture repair. Clinicians caring for perioperative hip fracture patients must pay particular attention to risk for, and implications of, new or recurrent heart failure.
Acknowledgements
The authors thank Donna K. Lawson, LPN, Kathy Wolfert, and Cherie Dolliver for their assistance in data collection and management.
As the population ages, hip fractures and heart failure increase in prevalence.1, 2 Heart failure prevalence is also increasing in hospitalized patients.3 Indeed, hospitalizations involving heart failure as an active issue tripled in the last 30 years.4 Heart failure has been associated with an increased risk for hip fracture,5, 6 and previous studies report a 6%20% prevalence of preoperative heart failure in hip fracture patients.710 While exacerbation of heart failure increases the mortality risk in patients admitted for hip fractures,8 the incidence of new heart failure, as well as the preoperative factors that predict postoperative heart failure in this patient population remain unclear.
American College of Cardiology/American Heart Association (ACC/AHA) perioperative guidelines identify orthopedic surgeries, including hip fracture repair, as intermediate risk procedures.11 Compared to other intermediate risk operations, however, postoperative outcomes following hip fracture repair differ significantly.1216 Overall mortality in hip fracture patients has been reported at 29% at one year,8 with the excess mortality from hip fracture alone at nearly 20%.10, 13 However, the exact factors that contribute to this excess mortality, particularly with regard to heart failure, remain unclear.
To examine the preoperative prevalence, subsequent incidence, and predictors of heart failure in patients undergoing hip fracture repair operations, this study used an established, population‐based database to compare the postoperative consequences in hip fracture repair patients with and without preexisting heart failure. We hypothesized that preoperative heart failure worsens postoperative outcomes in hip fracture patients.
METHODS
Case Ascertainment
Following approval by the Institutional Review Boards of Mayo Clinic and the Olmsted Medical Center, we used the Rochester Epidemiology Project (REP) to identify the patients for this study. The REP is a population‐based medical records linkage system that records all diagnoses, surgical procedures, laboratory data, and death information from hospital, emergency room, outpatient, and nursing home care in the community.17
All Olmsted County, Minnesota, residents who sustained a hip fracture and underwent surgical repair from 1988 through 2002 were evaluated. Patients with more than one hip fracture during the study period (96 occurrences) were censored from the data analysis at the time of the subsequent hip fracture and then included as new cases. The complete enumeration of hip fracture episodes managed in the three Olmsted County hospital facilities (Mayo Clinic's Saint Mary's and Rochester Methodist Hospitals, and the Olmsted Medical Center Hospital) occurred in three phases: First, all hospitalizations with the surgical procedure (International Statistical Classification of Diseases, 9th Revision [ICD‐9]) codes 79.15 (reduction, fracture, femur, closed with internal fixation), 79.25 (reduction, fracture, femur, open, without internal fixation), 79.35 (reduction, fracture, femur, open with internal fixation), 79.95 (operation, unspecified bone injury, femur), 80.05 (arthrotomy for removal of hip prosthesis), 80.15 (arthrotomy, other, hip), 80.95 (excision, hip joint), 81.21 (arthrodesis, hip), 81.40 (repair hip, not elsewhere classified), 81.51 (total hip replacement), 81.52 (partial hip replacement), and 81.53 (revision hip replacement) were identified. Second, through review of the original inpatient and outpatient medical records, we confirmed that a fracture was associated with the index hospitalization. Finally, radiology reports of each index hospitalization verified the presence and exact anatomical location of each fracture. Of those with fractures on admission x‐rays, only patients with a proximal femur (femoral neck or intertrochanteric) fracture as the primary indication for the surgery were included in the study. Surgical report or radiographic evidence of hip fracture was available for all patients. Secondary fractures due to a specific pathological lesion (eg, malignancy) or high‐energy trauma (by convention, motor vehicle accidents or falls from significant heights) were excluded. Only patients who had provided an authorization to review their medical records for research were ultimately included in the study cohort.18 Medical records were search manually, if indicated.
Criteria for Heart Failure and Death
Preoperative heart failure was based on clinical documentation of heart failure in a patient's medical record prior to the time of the hip fracture repair. Postoperative heart failure, including acute exacerbations, was defined according to Framingham criteria.19 Framingham criteria included clinical evidence of increased central venous pressure, pulmonary edema, an S3 gallop, radiographic pulmonary edema, and response to diuresis. Heart failure was not graded on clinical severity (ie, New York Heart Association classification). We did not distinguish between systolic and diastolic heart failure. Mortality was defined as death from any cause within the first year following hip fracture repair. Deaths were identified either through REP resources or the National Death Index.
Statistical Methods
Continuous variables are presented as mean standard deviation and categorical variables as number (percent). Two‐sample t tests or Wilcoxon rank sum tests were used to test for significant differences in continuous variables. Chi‐square or Fisher's exact tests were used for categorical variables. Rates of postoperative outcomes were calculated using the KaplanMeier method for the overall group and for those with and without preoperative heart failure. A landmark survival curve was used to evaluate postoperative mortality among patients who experienced heart failure in the first seven postoperative days versus those who did not. Patients who died or underwent another hip operation within the first seven postoperative days were excluded from this analysis. Univariate Cox proportional hazards models were used to evaluate the predictors of postoperative heart failure and mortality. Patients who died or experienced a second hip surgery within one year of their first were censored at that time. Any subsequent hip fracture repair was treated as a new case. To account for the inclusion of multiple hip fracture repairs for a given patient, the Cox proportional hazards model included a robust variance estimator. This provided an accurate calculation of the standard error in the presence of within‐subject correlation.20 Statistical tests were two‐sided, and P values were considered significant if less than 0.05. Statistical analyses were performed using SAS (version 9.1.3, SAS Institute, Cary, NC).
RESULTS
From among 1327 potential hip fracture repairs, we excluded 115 cases involving multiple injuries or operations (19), pathological fractures (20), in‐hospital fractures (3), or an operation >72 hours after the initial fracture (5). Three patients under 65 years of age were also excluded, as were cases with missing information (9) or cases managed nonoperatively (56). The final analysis included 1212 surgical cases in 1116 subjects. No subjects were lost to surveillance for 1 year following their hip fracture repair.
Table 1 summarizes the baseline characteristics of the study population. The overall prevalence of preoperative heart failure was 27.0% (327 of 1212). Those with preoperative heart failure were older, heavier, more likely male and white, and less likely to live independently preoperatively. They were also more likely to suffer from preexisting cardiovascular comorbidities.
All (N = 1,212) | HF (N = 327) | No HF (N = 885) | P Value* | |
---|---|---|---|---|
| ||||
Demographics | ||||
Mean age (years) (SD) | 84.2 (7.44) | 85.5 (6.54) | 83.7 (7.70) | 0.00101 |
Male gender | 237 (19.6) | 76 (23.2) | 161 (18.2) | 0.04912 |
Mean BMI (kg/m2) (SD) | 23.3 (4.97) | 24.1 (5.68) | 23.0 (4.65) | 0.01231 |
White | 1,204 (99.3) | 322 (98.5) | 882 (99.7) | 0.03713 |
Preoperative living situation | ||||
Nursing facility | 468 (38.6) | 144 (44) | 324 (36.6) | 0.01842 |
Home | 744 (61.4) | 183 (56) | 561 (63.4) | 0.05192 |
Preoperative ambulatory status | ||||
Dependent | 149 (12.3) | 50 (15.3) | 99 (11.2) | |
Independent | 1,061 (87.7) | 276 (84.7) | 785 (88.8) | |
Medical history | ||||
Hypertension | 705 (58.2) | 226 (69.1) | 479 (54.1) | <0.00012 |
Diabetes mellitus | 143 (11.8) | 63 (19.3) | 80 (9) | <0.00012 |
Cerebrovascular disease | 331 (27.3) | 129 (39.4) | 202 (22.8) | <0.00012 |
Peripheral vascular disease | 195 (16.1) | 80 (24.5) | 115 (13) | <0.00012 |
Coronary artery disease | 464 (38.3) | 237 (72.5) | 227 (25.6) | <0.00012 |
Atrial fibrillation/flutter | 254 (21) | 133 (40.7) | 121 (13.7) | <0.00012 |
Complete heart block | 18 (1.5) | 9 (2.8) | 9 (1) | 0.03373 |
Pacer at time of admission | 32 (2.6) | 16 (4.9) | 16 (1.8) | 0.00292 |
Chronic obstructive pulmonary disease | 196 (16.2) | 78 (23.9) | 118 (13.3) | <0.00012 |
Liver disease | 15 (1.2) | 7 (2.1) | 8 (0.9) | 0.13753 |
Chronic renal insufficiency | 131 (10.8) | 61 (18.7) | 70 (7.9) | <0.00012 |
Mean length of hospitalization (days) (SD) | 10.0 (7.57) | 11.1 (8.82) | 9.6 (7.01) | 0.00101 |
Discharge disposition | 0.00192 | |||
Home | 150 (12.4) | 26 (8.0) | 124 (14.0) | |
Skilled nursing facility | 1,004 (82.9) | 278 (85.0) | 726 (82.1) | |
Dead | 57 (4.7) | 23 (7.0) | 34 (3.9) |
Table 1 also summarizes the main outcome characteristics of the study population. Those with preoperative heart failure had longer mean lengths of stay (LOS), were more often discharged to a skilled facility, and demonstrated higher inpatient mortality rates.
Table 2 summarizes the outcomes associated with preoperative heart failure. The overall rate of postoperative heart failure was 6.7% within 7 postoperative days and 21.3% within 1 postoperative year. Postoperative heart failure was significantly more common among those with preoperative heart failure (hazard ratio [HR], 3.0; 95% confidence interval [CI], 2.3 to 3.9; P < 0.001). Among those without preoperative heart failure, rates of postoperative incident heart failure were 4.8% at 7 days and 15.0% at 1 year. Compared to patients without preoperative heart failure, those with preoperative heart failure demonstrated higher one year mortality rates and higher rates of postoperative heart failure at 7 days and 1 year.
Preoperative Heart Failure (Subjects) | |||||
---|---|---|---|---|---|
Outcome | All (N = 1212) | No (N = 885) | Yes (N = 327) | Risk ratio* (95% CI) | P Value |
| |||||
Heart failure exacerbation within seven postoperative days | 6.7% (5.4, 8.3) | 4.8% (3.5, 6.5) | 12.1% (8.7, 16.2) | 2.72 (1.72, 4.31) | <0.0001 |
One‐year postoperative heart failure exacerbation | 21.3% (18.8, 23.7) | 15.0% (12.5, 17.4) | 39.3% (33.3, 44.9) | 3.00 (2.32, 3.87) | <0.0001 |
One‐year postoperative mortality | 24.5% (22.0, 26.9) | 19.8% (17.1, 22.4) | 37.2% (31.6, 42.3) | 2.11 (1.67, 2.67) | <0.0001 |
One‐year postoperative mortality or heart failure exacerbation | 36.5% (33.7, 39.2) | 29.7% (26.6, 32.6) | 55.0% (49.3, 60.2) | 2.28 (1.88, 2.76) | <0.0001 |
Figure 1 displays the outcomes to 1 year of surveillance. Rates of postoperative heart failure and postoperative mortality were consistently higher among those with, versus without, preoperative heart failure. Figure 2 displays similar data stratified by gender. Postoperative heart failure rates did not differ significantly between genders (HR, 1.0; 95% CI, 0.8 to 1.4), but postoperative mortality rates were significantly higher among males than females (HR, 1.9; 95% CI, 1.5 to 2.5; P < 0.001).
Figure 3 displays survival rates to 1 year based on the occurrence of incident or recurrent heart failure within the first 7 postoperative days. Survival rates were lowest among patients with recurrent heart failure in the first 7 postoperative days and highest among those with no preoperative or postoperative heart failure. Subjects with incident heart failure in the first postoperative week, and those with preoperative heart failure who did not suffer a recurrence, demonstrated intermediate survival rates (P < 0.001 for trend across all four groups).
DISCUSSION
This population‐based study found that heart failure represents a highly prevalent condition in elderly patients undergoing hip fracture repairs. It demonstrates that those with preoperative heart failure typically suffer from more cardiovascular comorbidities and carry a higher risk of postoperative heart failure and postoperative mortality.
While many studies have focused on the epidemiology of hip fractures,21 population‐based data on cardiac complications following hip fracture repair are significantly less common. The ACC/AHA preoperative cardiac evaluation guidelines classify orthopedic procedures, including hip fracture repair, as intermediate risk.11 Consequently, some may assume that all orthopedic patients will have a mortality rate less than 5%. Indeed, the 30‐day postoperative mortality rate published from our institution's Total Joint Registry was 0.6% following elective total hip arthroplasty.22 However, the present study demonstrates that current ACC/AHA preoperative cardiac evaluation guidelines may not apply to the population of frail patients undergoing hip fracture repair. Particularly among those who experience new heart failure within the first seven days following surgery, outcomes are substantially worse than the ACC/AHA perioperative guidelines may suggest.11
Preoperative heart failure has been associated with adverse risk for postoperative mortality after hip fracture.9, 10, 12 However, these studies did not report heart failure as a complication of hip fracture repair. A prospective cohort study of 2448 hip fracture patients at an academic hospital in Great Britain found a 5% rate of inpatient heart failure as a postoperative complication.23 The hazard ratio for one‐year mortality was 11.3 with postoperative heart failure.23 However, the British study did not distinguish heart failure from other cardiovascular diseases as a preoperative comorbidity or stratify the risk for postoperative mortality by preoperative heart failure status.23 Our findings add to previous literature by measuring heart failure as a specific complication of hip fracture repair and examining the association of preoperative heart failure with postoperative heart failure and mortality.
Length of stay after hip fracture repair varies in the literature, but previous work has not clearly associated heart failure with length of hospitalization in the setting of hip fracture repair.24, 25 Our study found a significantly higher mean length of stay among those with preoperative heart failure. This adds to previous work by delineating an association between heart failure and increased length of stay after hip fracture repair.
We found a higher rate of postoperative mortality among men compared to women. Rates of postoperative heart failure, however, were more similar (Figure 2). Previous studies have found a consistently higher mortality rate among men versus women after hip fracture.9, 23, 2529 Possible explanations for these findings include the overall increased burden of cardiovascular disease among men, lower treatment rates of osteoporosis in men,30 and increased susceptibility to other postoperative complications, such as infection.25
The findings of this study carry important clinical implications for the perioperative care of hip fracture patients with, or at risk for, heart failure. They suggest that current risk stratification guidelines classifying orthopedic operations as intermediate risk procedures do not reflect the high risk for morbidity that hip fracture patients face.11 The association of heart failure with adverse outcomes implies the need for heightened surveillance in the perioperative period, particularly with regard to volume status and medication reconciliation. Hip fracture patients and their families must be counseled about the ramifications of perioperative heart failure, including higher rates of postoperative heart failure, longer hospitalizations, and ultimate mortality.
This research carries several limitations and remains subject to biases inherent in retrospective cohort studies. The reported effects of heart failure on outcomes after hip fracture repair may be due to confounding from age, functional status, and other comorbidities. We attempted to minimize sampling bias through complete enumeration of hip fracture surgeries among Olmsted County residents. Completeness of follow‐up (100% at one year) was possible given the availability of documentation of all inpatient and outpatient medical care in the community.17 We used objectively defined outcomes to minimize measurement bias. Applicability to a more diverse population may be limited because >95% of the research population was from a single, predominantly white community. However, prior studies have documented that hip fracture incidence rates31 and socioeconomic factors17 in Olmsted County are similar to those for other white residents of the United States. Heart failure rates were determined clinically according to the Framingham criteria. However, the Framingham criteria may inappropriately diagnose individuals with heart failure32 and falsely elevate the prevalence of heart failure as a preoperative comorbidity or postoperative complication.
The statistical analysis included patients counted multiple times if they underwent subsequent hip fracture repair during the study period. Including these patients may inaccurately inflate event rates or contribute to incorrect estimates of standard error. However, we felt it was appropriate to include recurrent hip fracture repair cases in the analysis because they represent a clinically distinct patient from both a medical and functional perspective. We used a robust variance estimator in the Cox proportional hazards models to provide an accurate calculation of the standard error given the possibility for correlation within subjects.20 Finally, the proportion of these patients was low (94 of 1116 unique patients; 8.4%).
Future work must involve further risk stratification and therapeutic interventions in perioperative hip fracture patients. A more robust analysis of heart failure, with differentiation between systolic and diastolic dysfunction, may facilitate risk stratification. Assessment of compliance with standard preoperative heart failure medications and the impact of heightened clinical vigilance may enlighten means to improve postoperative outcomes. Studies on risk stratification and therapeutic interventions may then inform policy regarding length of stay and reimbursement in hip fracture patients.
CONCLUSION
In summary, our population‐based findings reveal that heart failure represents a prevalent and serious comorbidity in patients undergoing hip fracture repair. Clinicians caring for perioperative hip fracture patients must pay particular attention to risk for, and implications of, new or recurrent heart failure.
Acknowledgements
The authors thank Donna K. Lawson, LPN, Kathy Wolfert, and Cherie Dolliver for their assistance in data collection and management.
- Epidemiology of hip fractures: Implications of the exponential increase with age.Bone.1996;18(3 suppl):121S–125S. .
- Trends in length of stay and short‐term outcomes among Medicare patients hospitalized for heart failure, 1993–2006.JAMA.2010;303(21):2141–2147. , , , et al.
- The expanding national burden of heart failure in the United States: The influence of heart failure in women.Am Heart J.2004;147(1):74–78. , , , , .
- Heart failure‐related hospitalization in the U.S., 1979 to 2004.J Am Coll Cardiol.2008;52(6):428–434. , , , .
- Heart failure is a risk factor for orthopedic fracture: A population‐based analysis of 16,294 patients.Circulation.2008;118(19):1946–1952. , , , , .
- Cardiovascular diseases and risk of hip fracture.JAMA.2009;302(15):1666–1673. , , , et al.
- Effectiveness of hospitalist involvement in hip fracture management questioned.South Med J.2007;100(9):912–913. , , , .
- Effects of a hospitalist care model on mortality of elderly patients with hip fractures.J Hosp Med.2007;2(4):219–225. , , , et al.
- Excess mortality in men compared with women following a hip fracture. National analysis of comedications, comorbidity and survival.Age Ageing.2010;39(2):203–209. , , , .
- Increased mortality in patients with a hip fracture—Effect of pre‐morbid conditions and post‐fracture complications.Osteoporos Int.2007;18(12):1583–1593. , , .
- ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: Executive summary: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery): Developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, and Society for Vascular Surgery.J Am Coll Cardiol.2007;50(17):1707–1732. , , , et al.
- Excess mortality following hip fracture: The role of underlying health status.Osteoporos Int.2007;18(11):1463–1472. , , , , .
- Time trends of mortality after first hip fractures.Osteoporos Int.2007;18(6):721–732. .
- Mortality and locomotion 6 months after hospitalization for hip fracture: Risk factors and risk‐adjusted hospital outcomes.JAMA.2001;285(21):2736–2742. , , , et al.
- Factors associated with mortality after hip fracture.Osteoporos Int.2000;11(3):228–232. , , , .
- Hip fractures among the elderly: Factors associated with in‐hospital mortality.Am J Epidemiol.1991;134(10):1128–1137. , , , , , .
- History of the Rochester Epidemiology Project.Mayo Clin Proc.1996;71(3):266–274. .
- The threat to medical‐records research.N Engl J Med.1997;337(20):1466–1470. .
- The natural history of congestive heart failure: The Framingham Study.N Engl J Med.1971;285(26):1441–1446. , , , .
- The robust inference for the Cox proportional hazards model.J Am Stat Assoc.1989;84(408):1074–1078. , .
- Hip fracture epidemiological trends, outcomes, and risk factors, 1970–2009.Int J Gen Med.2010;3:1–17. .
- Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty.Anesthesiology.2002;96(5):1140–1146. , , , , , .
- Effect of comorbidities and postoperative complications on mortality after hip fracture in elderly people: Prospective observational cohort study.BMJ.2005;331(7529):1374–1376. , , , .
- The aftermath of hip fracture: Discharge placement, functional status change, and mortality.Am J Epidemiol.2009;170(10):1290–1299. , , , et al.
- Gender differences in mortality after hip fracture: The role of infection.J Bone Miner Res.2003;18(12):2231–2237. , , , , , .
- Mortality after all major types of osteoporotic fracture in men and women: An observational study.Lancet.1999;353(9156):878–882. , , , , .
- Adjusted mortality after hip fracture: From the Cardiovascular Health Study.J Am Geriatr Soc.2006;54(12):1885–1891. , , .
- Meta‐analysis: Excess mortality after hip fracture among older women and men.Ann Intern Med.2010;152(6):380–390. , , , et al.
- Predictors of hip fractures in elderly men.J Bone Miner Res.1995;10(12):1900–1907. , , , .
- Population‐based fracture risk assessment and osteoporosis treatment disparities by race and gender.J Gen Intern Med.2009;24(8):956–962. , , , et al.
- Long‐term trends in hip fracture prevalence: The influence of hip fracture incidence and survival.Osteoporos Int.1998;8(1):68–74. , , .
- diagnostic accuracy of clinical criteria for identifying systolic and diastolic heart failure: Cross‐sectional study.J Eval Clin Pract.2009;15(1):55–61. , , , , , .
- Epidemiology of hip fractures: Implications of the exponential increase with age.Bone.1996;18(3 suppl):121S–125S. .
- Trends in length of stay and short‐term outcomes among Medicare patients hospitalized for heart failure, 1993–2006.JAMA.2010;303(21):2141–2147. , , , et al.
- The expanding national burden of heart failure in the United States: The influence of heart failure in women.Am Heart J.2004;147(1):74–78. , , , , .
- Heart failure‐related hospitalization in the U.S., 1979 to 2004.J Am Coll Cardiol.2008;52(6):428–434. , , , .
- Heart failure is a risk factor for orthopedic fracture: A population‐based analysis of 16,294 patients.Circulation.2008;118(19):1946–1952. , , , , .
- Cardiovascular diseases and risk of hip fracture.JAMA.2009;302(15):1666–1673. , , , et al.
- Effectiveness of hospitalist involvement in hip fracture management questioned.South Med J.2007;100(9):912–913. , , , .
- Effects of a hospitalist care model on mortality of elderly patients with hip fractures.J Hosp Med.2007;2(4):219–225. , , , et al.
- Excess mortality in men compared with women following a hip fracture. National analysis of comedications, comorbidity and survival.Age Ageing.2010;39(2):203–209. , , , .
- Increased mortality in patients with a hip fracture—Effect of pre‐morbid conditions and post‐fracture complications.Osteoporos Int.2007;18(12):1583–1593. , , .
- ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: Executive summary: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery): Developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, and Society for Vascular Surgery.J Am Coll Cardiol.2007;50(17):1707–1732. , , , et al.
- Excess mortality following hip fracture: The role of underlying health status.Osteoporos Int.2007;18(11):1463–1472. , , , , .
- Time trends of mortality after first hip fractures.Osteoporos Int.2007;18(6):721–732. .
- Mortality and locomotion 6 months after hospitalization for hip fracture: Risk factors and risk‐adjusted hospital outcomes.JAMA.2001;285(21):2736–2742. , , , et al.
- Factors associated with mortality after hip fracture.Osteoporos Int.2000;11(3):228–232. , , , .
- Hip fractures among the elderly: Factors associated with in‐hospital mortality.Am J Epidemiol.1991;134(10):1128–1137. , , , , , .
- History of the Rochester Epidemiology Project.Mayo Clin Proc.1996;71(3):266–274. .
- The threat to medical‐records research.N Engl J Med.1997;337(20):1466–1470. .
- The natural history of congestive heart failure: The Framingham Study.N Engl J Med.1971;285(26):1441–1446. , , , .
- The robust inference for the Cox proportional hazards model.J Am Stat Assoc.1989;84(408):1074–1078. , .
- Hip fracture epidemiological trends, outcomes, and risk factors, 1970–2009.Int J Gen Med.2010;3:1–17. .
- Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty.Anesthesiology.2002;96(5):1140–1146. , , , , , .
- Effect of comorbidities and postoperative complications on mortality after hip fracture in elderly people: Prospective observational cohort study.BMJ.2005;331(7529):1374–1376. , , , .
- The aftermath of hip fracture: Discharge placement, functional status change, and mortality.Am J Epidemiol.2009;170(10):1290–1299. , , , et al.
- Gender differences in mortality after hip fracture: The role of infection.J Bone Miner Res.2003;18(12):2231–2237. , , , , , .
- Mortality after all major types of osteoporotic fracture in men and women: An observational study.Lancet.1999;353(9156):878–882. , , , , .
- Adjusted mortality after hip fracture: From the Cardiovascular Health Study.J Am Geriatr Soc.2006;54(12):1885–1891. , , .
- Meta‐analysis: Excess mortality after hip fracture among older women and men.Ann Intern Med.2010;152(6):380–390. , , , et al.
- Predictors of hip fractures in elderly men.J Bone Miner Res.1995;10(12):1900–1907. , , , .
- Population‐based fracture risk assessment and osteoporosis treatment disparities by race and gender.J Gen Intern Med.2009;24(8):956–962. , , , et al.
- Long‐term trends in hip fracture prevalence: The influence of hip fracture incidence and survival.Osteoporos Int.1998;8(1):68–74. , , .
- diagnostic accuracy of clinical criteria for identifying systolic and diastolic heart failure: Cross‐sectional study.J Eval Clin Pract.2009;15(1):55–61. , , , , , .
Copyright © 2011 Society of Hospital Medicine
Hospitalists and Hip Fractures
Because the incidence of hip fracture increases dramatically with age and the elderly are the fastest‐growing portion of the United States population, the number of hip fractures is expected to triple by 2040.1 With the associated increase in postoperative morbidity and mortality, the costs will likely exceed $16‐$20 billion annually.15 Already by 2002, the number of patients with hip fractures exceeded 340,000 in this country, resulting in $8.6 billion in health care expenditures from in‐hospital and posthospital costs.68 This makes hip fracture a serious public health concern and triggers a need to devise an efficient means of caring for these patients. We previously reported that a hospitalist service can decrease time to surgery and shorten length of stay without affecting the number of inpatient deaths or 30‐day readmissions of patients undergoing hip fracture surgery.9 However, one concern with reducing length of stay and time to surgery in the high‐risk hip fracture patient population is the effect on long‐term mortality because the death rate following hip fracture repair may be as high as 43% after 1 year.10 To evaluate this important issue, we assessed mortality over a 1‐year period in the same cohort of patients previously described.9 We also identified predictors associated with mortality. We hypothesized that the expedited surgical treatment and decreased length of stay of a hospitalist‐managed group would not have an adverse effect on 1‐year mortality.
METHODS
Patient Selection
Following approval by the Mayo Clinic Institutional Review Board, we used the Mayo Clinic Surgical Index to identify patients admitted between July 1, 2000, and June 30, 2002, who matched International Classification of Diseases (9th Edition) hip fracture codes.11 These patients were cross‐referenced with those having a primary surgical indication of hip fracture. Patients transferred to our facility more than 72 hours after fracture were excluded from our study. Study patients provided authorization to use their medical records for the purposes of research.
A cohort of 466 patients was identified. For purposes of comparison, patients admitted between July 1, 2000, and June 30, 2001, were deemed to belong to the standard care service, and patients admitted between July 1, 2001, and June 30, 2002, were deemed part of the hospitalist service.
Intervention
Prior to July 2001, Mayo Clinic patients aged 65 and older having surgical repair of a hip fracture were triaged directly to a surgical orthopedic or general medical teaching service. Patients with multiple medical diagnoses were managed initially on a medical teaching service prior to transfer to the operating room. The primary team (medical or surgical) was responsible for the postoperative care of the patient and any orders or consultations required.
After July 1, 2001, these patients were admitted by the orthopedic surgery service and medically comanaged by a hospitalist service, which consisted of a hospitalist physician and 2 allied‐health practitioners. Twelve hospitalists and 12 allied health care professionals cared for patients during the study period. All preoperative and postoperative evaluations, inpatient management decisions, and coordination of outpatient care were performed by the hospitalists. This model of care is similar to one previously studied and published elsewhere.12 A census cap of 20 patients limited the number of patients managed by the hospitalist service. Any overflow of hip fracture patients was triaged directly to a non‐hospitalist‐based primary medical or surgical service as before. Thus, 23 hip fracture patients (10%) admitted after July 1, 2001, were not managed by the hospitalists but are included in this group for an intent‐to‐treat analysis.
Data Collection
Study nurses abstracted all data including admitting diagnoses, demographic features, type and mechanism of hip fracture, admission date and time, American Society of Anesthesia (ASA) class, comorbid medical conditions, medications, all clinical data, and readmission rates. Date of last follow‐up was confirmed using the Mayo Clinic medical record, whereas date and cause of death were obtained from death certificates obtained from state and national sources. Length of stay was defined as the number of days between admission and discharge. Time to surgery was defined in hours as the time from hospital admission to the start of the surgery. Finally, time from surgery to dismissal was defined as the number of days from the initiation of the surgical procedure to the time of dismissal. Thirty‐day readmission was defined as readmission to our hospital within 30 days of discharge date.
Statistical Considerations
Power
The power analysis was based on the end point of survival following surgical repair of hip fracture and primary comparison of patients in the standard care group with those in the hospitalist group. With 236 patients in the standard care group, 230 in the hospitalist group, and 274 observed deaths during the follow‐up period, there was 80% power to detect a hazard ratio of 1.4 or greater as being statistically significant (alpha = 0.05, beta = 0.2).
Analysis
The analysis focused on the end point of survival following surgical repair of hip fracture. In addition to the hospitalist versus standard care service, demographic, baseline clinical, and in‐hospital data were evaluated as potential predictors of survival. Survival rates were estimated using the method of Kaplan and Meier, and relative differences in survival were evaluated using the Cox proportional hazards regression models.13, 14 Potential predictors were analyzed both univariately and in a multivariable model. For the multivariable model, initial variable selection was accomplished using stepwise selection, backward elimination, and recursive partitioning.15 Each method yielded similar results. Bootstrap resampling was then used to confirm the variables selected for each model.16, 17 The threshold of statistical significance was set at P = .05 for all tests. All analyses were conducted in SAS version 8.2 (SAS Institute Inc., Cary, NC) and Splus version 6.2.1 (Insightful Corporation, Seattle, WA).
RESULTS
There were 236 patients with hip fractures (50.6%) admitted to the standard care service, and 230 patients (49.4%) admitted to the hospitalist service. As shown in Table 1, the baseline characteristics of the patients admitted to the 2 services did not differ significantly except that a greater proportion of patients with hypoxia were admitted to the hospitalist service (11.3% vs. 5.5%; P = .02). However, time to surgery, postsurgery stay, and overall length of hospitalization of the hospitalist‐treated patients were all significantly shorter.
Patient characteristic | Standard care n = 236 | Hospitalist care n = 230 | P value | ||
---|---|---|---|---|---|
| |||||
Age (years) | 82 | 83 | .34 | ||
Female sex | 171 | 72.5% | 163 | 70.9% | .70 |
Comorbidity | |||||
Coronary artery disease | 69 | 29.2% | 77 | 33.5% | .32 |
Congestive heart failure | 41 | 17.4% | 49 | 21.3% | .28 |
Chronic obstructive pulmonary disease | 36 | 15.3% | 38 | 16.5% | .71 |
Cerebral vascular accident or transient ischemic attack | 36 | 15.3% | 50 | 21.7% | .07 |
Dementia | 54 | 22.9% | 62 | 27.0% | .31 |
Diabetes | 45 | 19.1% | 46 | 20.0% | .80 |
Renal insufficiency | 17 | 7.2% | 17 | 7.4% | .94 |
Residence at time of admission | .07 | ||||
Home | 149 | 63.1% | 138 | 60.0% | |
Assisted living | 32 | 13.6% | 42 | 18.3% | |
Nursing home | 55 | 23.3% | 50 | 21.7% | |
Ambulatory status at time of admission | .14 | ||||
Independent | 114 | 48.3% | 89 | 38.7% | |
Assistive device | 99 | 41.9% | 115 | 50.0% | |
Personal help | 9 | 3.8% | 16 | 7.0% | |
Transfer to bed or chair | 9 | 3.8% | 7 | 3.0% | |
Nonambulatory | 5 | 2.1% | 3 | 1.3% | |
Signs at time of admission | |||||
Hypotension | 4 | 1.7% | 3 | 1.3% | > .99 |
Hypoxia | 13 | 5.5% | 26 | 11.3% | .02 |
Pulmonary edema | 37 | 15.7% | 29 | 12.6% | .34 |
Tachycardia | 19 | 8.1% | 25 | 10.9% | .3 |
Fracture type | .78 | ||||
Femoral neck | 118 | 50.0% | 118 | 51.3% | |
Intertrochanteric | 118 | 50.0% | 112 | 48.7% | |
Mechanism of fracture | .82 | ||||
Fall | 219 | 92.8% | 212 | 92.2% | |
Trauma | 1 | 0.4% | 3 | 1.3% | |
Pathologic | 7 | 3.0% | 6 | 2.6% | |
Unknown | 9 | 3.8% | 7 | 3.0% | |
ASA* class | .38 | ||||
I or II | 33 | 14.0% | 23 | 10.0% | |
III | 166 | 70.3% | 166 | 72.2% | |
IV | 37 | 15.7% | 41 | 17.8% | |
Location discharged to | .07 | ||||
Home or assisted living | 24 | 10.5% | 13 | 5.9% | |
Nursing home | 196 | 86.0% | 192 | 87.3% | |
Another hospital or hospice | 8 | 3.5% | 15 | 6.8% | |
Time to surgery (hours) | 38 | 25 | .001 | ||
Time from surgery to discharge (days) | 9 | 7 | .04 | ||
Length of stay | 10.6 | 8.4 | < .00 | ||
Readmission rate | 25 | 10.6% | 20 | 8.7% | .49 |
Patients were followed for a median of 4.0 years (range 5 days to 5.6 years), and 192 patients were still alive at the end of follow‐up (April 2006). As illustrated in Figure 1, survival did not differ between the 2 treatment groups (P = .36). Overall survival at 1 year was 70.6% (95% confidence interval [CI]: 66.5%, 74.9%). Survival at 1 year in the standard care group was 70.6% (95% CI: 64.9%, 76.8%), whereas in the hospitalist group, it was 70.5% (95% CI: 64.8%, 76.7%). As delineated in Table 2, cardiovascular causes accounted for 34 deaths (25.6%), with 14 of these in the standard care group and 20 in the hospitalist group; 29 deaths (21.8%) had respiratory causes, 20 in the standard care group and 9 in the hospitalist group; and 17 (12.8%) were due to cancer, with 7 and 10 in the standard care and hospitalist groups, respectively. Unknown causes accounted for 21 cases, or 15.8% of total deaths.
Standard care | Hospitalist care | Total No. of deaths | % | |
---|---|---|---|---|
Cancer | 7 | 10 | 17 | 12.8% |
Cardiovascular | 14 | 20 | 34 | 25.6% |
Infectious | 5 | 4 | 9 | 6.8% |
Neurological | 5 | 10 | 15 | 11.3% |
Other | 0 | 2 | 2 | 1.5% |
Renal | 4 | 2 | 6 | 4.5% |
Respiratory | 20 | 9 | 29 | 21.8% |
Unknown | 11 | 10 | 21 | 15.8% |
Total | 66 | 67 | 133 | 100.0% |
In the univariate analysis, we found 29 variables that were significant predictors of survival (Table 3). A hospitalist model of care was not significantly associated with patient survival, despite the shorter length of stay (8.4 days vs. 10.6 days; P < .001) or expedited time to surgery (25 vs. 38 hours; P < .001), when compared with the standard care group, as previously reported by Phy et al.9 In the multivariable analysis (Table 4), however, the independent predictors of mortality were ASA class III or IV versus class II (hazard ratio [HR] 4.20; 95% CI: 2.21, 7.99), admission from a nursing home versus from home or assisted living (HR 2.24; 95% CI: 1.73, 2.90), and inpatient complications, which included patients requiring admission to the intensive care unit (ICU) and those who had a myocardial infarction or acute renal failure as an inpatient (HR 1.85; 95% CI: 1.45, 2.35). Even after adjusting for these factors, survival following hip fracture did not differ significantly between the hospitalist care patients and the standard care patients (HR 1.16; 95% CI: 0.91, 1.48).
Variable | Hazard ratio (95% CI) | P value |
---|---|---|
| ||
Age on admission per 10 years | 1.41 (1.20, 1.65) | < .001 |
ASA* II | 1.0 (referent) | |
ASA* III | 5.27 (2.79, 9.96) | < .001 |
ASA* IV | 11.7 (5.97, 22.9) | < .001 |
History of chronic obstructive pulmonary disease | 1.82 (1.35, 2.43) | < .001 |
History of renal insufficiency | 2.40 (1.62,3.55) | < .001 |
History of stroke/transient ischemic attack | 1.46 (1.10, 1.95) | .01 |
History of diabetes | 1.70 (1.29,2.25) | < .001 |
History of congestive heart failure | 2.26 (1.73, 2.96) | < .001 |
History of coronary artery disease | 1.53 (1.20, 1.97) | < .001 |
History of dementia | 2.02 (1.57, 2.59) | < .001 |
Admission from home | 1.0 (referent) | |
Admission from assisted living | 1.47 (1.06, 2.04) | .02 |
Admission from nursing home | 3.04 (2.33, 3.98) | < .001 |
Independent | 1.0 (referent) | |
Use of assistive device | 1.81 (1.39, 2.36) | < .001 |
Personal help | 3.49 (2.16, 5.64) | < .001 |
Nonambulatory | 3.96 (2.47, 6.35) | < .001 |
Crackles on admission | 2.03 (1.50, 2.74) | < .001 |
Hypoxia on admission | 1.56 (1.04, 2.32) | .03 |
Hypotension on admission | 6.21 (2.72, 14.2) | < .001 |
Tachycardia on admission | 1.66 (1.15, 2.41) | .007 |
Coumadin on admission | 1.57 (1.13, 2.18) | .007 |
Confusion/unconsciousness on admission | 2.23 (1.74, 2.87) | < .001 |
Fever on admission | 1.98 (1.16, 3.40) | .01 |
Tachypnea on admission | 1.95 (1.39, 2.72) | < .001 |
Inpatient myocardial Infarction | 3.59 (2.35, 5.48) | < .001 |
Inpatient atrial fibrillation | 2.00 (1.37, 2.92) | < .001 |
Inpatient congestive heart failure | 2.62 (1.79, 3.84) | < .0001 |
Inpatient delirium | 1.46 (1.13, 1.90) | < .005 |
Inpatient lung infection | 2.52 (1.85, 3.42) | < .001 |
Inpatient respiratory failure | 2.76 (1.64, 4.66) | < .001 |
Inpatient mechanical ventilation | 2.56 (1.43, 4.57) | .002 |
Inpatient renal failure | 3.60 (1.97, 6.61) | < .001 |
Days from admission to surgery | 1.06 (1.005, 1.12) | .03 |
Intensive care unit stay | 1.93 (1.51, 2.47) | < .001 |
Variable | Hazard ratio (95% CI) | P value |
---|---|---|
| ||
Age on admission per 10 years | 1.17 (0.99, 1.38) | .07 |
ASA* class III or IV | 4.20 (2.21, 7.99) | < .001 |
ASA* class II | 1.0 (referent) | |
Admission from nursing home | 2.24 (1.73, 2.90) | < .001 |
Admission from home or assisted living | 1.0 (referent) | |
Inpatient myocardial infarction, inpatient acute renal failure, or intensive care unit stay | 1.85 (1.45, 2.35) | < .001 |
No inpatient myocardial infarction, no inpatient acute renal failure, and no intensive care unit stay | 1.0 (referent) |
DISCUSSION
In our previous study, length of stay and time to surgery were significantly lower in a hospitalist care model.9 The present study shows that neither the reduced length of stay nor the shortened time to surgery of patients managed by the hospitalist group was associated with a difference in mortality compared with a standard care group, despite significantly improved efficiency and processes of care. Thus, our results refute initial concerns of increased mortality in a hospitalist model of care.
Delivery of perioperative medical care to hip fracture patients by hospitalists is associated with significant decreases in time to surgery and length of stay compared with standard care, with no differences in short‐term mortality.9, 18 Although there have been conflicting reports on the impact of length of stay and time to surgery on long‐term outcomes, our findings support previous results that decreased time to surgery was not associated with an observable effect on mortality.1923 A recent study by Orosz et al. that evaluated 1178 patients showed that earlier hip fracture surgery (performed less than 24 hours after admission) was not associated with reduced mortality, although it was associated with shorter length of stay.19 Our study also corroborates the results of an examination of 8383 hip fracture patients by Grimes et al., who found that time to surgery between 24 and 48 hours after admission had no effect on either 30‐day or long‐term mortality compared with that of those who underwent surgery between 48 and 72 hours, between 72 and 96 hours, or more than 96 hours after admission.20 However, both these results and our own are contrary to those of Gdalevich, whose study of 651 patients found that 1‐year mortality was 1.6‐fold higher for those whose hip fracture repair was postponed more than 48 hours.21 However, time to surgery in both the standard care and hospitalist model in our study was well below the 48‐hour cutoff, suggesting that operating anywhere within the normally accepted 48‐hour time frame may not influence long‐term mortality.
Because of the small number of events in both groups, we were unable to specifically compare whether a hospitalist model of care has any specific impact on long‐term cause of death. Although causes of death of patients with hip fracture were consistent with those of previous studies,10, 24 our death rate at 1 year, 29.4%, was higher than that seen among similar population groups at tertiary referral centers.19, 20, 2429 This is most likely a result of the cohort having a high proportion of nursing home patients (22%)19, 24, 26 transferred for evaluation to St. Mary's Hospital, which serves most of Olmsted County, Minnesota. This hospital also has some characteristics of a community‐based hospital, as it is where greater than 95% of all county patients receive care for surgical repair of hip fracture. Mortality rates are often higher at these types of hospitals.30 Previous studies using patients from Olmsted County indicate results can also be extrapolated to a large part of the U.S. population.31 In Pitto et al.'s study, the risk of death was 31% lower in those admitted from home than for those admitted from a nursing home.32 The latter patients normally have a higher number of comorbid conditions and tend to be less ambulatory than those in a community home‐dwelling setting. Our study also demonstrated that admission from a nursing home was a strong predictor of mortality for up to 1 year in the geriatric population. This may reflect the inherent decreased survival in this patient group, which is in agreement with the findings of other studies that showed inactivity and decreased ambulation prior to fracture were associated with increased mortality.3335
Multiple comorbidities, commonly seen in a geriatric population, translate into a higher ASA class and an increased risk of significant in‐hospital complications. Our study confirmed the findings of previous studies that a higher ASA class is a strong predictor of mortality,21, 26, 30, 3537 independent of decreased time to surgery.38 We also noted that significant in‐hospital complications, including renal failure, respiratory failure, and myocardial infarction, are documented predictors of mortality after hip fracture.27 Although mortality may vary depending on fracture type (femoral neck vs. intertrochanteric),3941 these differences were not observed in our study, in line with the results of previous published studies.37, 42 Controlling for age and comorbidities may be why an association was not found between fracture type and mortality. Finally, in a model containing comorbidity, ASA class, and nursing home residence prior to fracture, age was not a significant predictor of mortality.
Our study had a number of limitations. First, this was a retrospective cohort study based on chart review, so some data may have been subject to recording bias, and this might have differed between the serial models. Because of the retrospective nature of the study and referral of some of the patients from outside the community, our 1‐year follow‐up was not complete, but approached a respectable 93%. Other studies have described the benefits derived by a hospitalist practice only following the first year of its implementation, likely because of the hospitalist learning curve.43, 44 This may be why there was no difference in mortality between the standard care and hospitalist groups, as the latter was only in its first year of existence. Additional longitudinal study is required to find out if mortality differences emerge between the treatment groups. Furthermore, although in‐hospital care may influence short‐term outcomes, its effect on long‐term mortality has been unclear. Our data demonstrate that even though a hospitalist service can shorten length of stay and time to surgery, there were no appreciable intermediate differences in mortality at 1 year. Further prospective studies are needed to determine whether this medical‐surgical partnership in caring for these patients provides more favorable outcomes of reducing mortality and intercurrent complications.
Acknowledgements
We thank Donna K. Lawson for her assistance in data collection and management.
- The future of hip fractures in the United States. Numbers, costs, and potential effects of postmenopausal estrogen.Clin Orthop Relat Res1990 (252):163–166. , , .
- Hip fractures in the elderly: a world‐wide projection.Osteoporos Int.1992;2:285–289. , , .
- The economic cost of hip fractures among elderly women. A one‐year, prospective, observational cohort study with matched‐pair analysis.Belgian Hip Fracture Study Group.J Bone Joint Surg Am.2001;83‐A:493–500. , , , .
- Estimating hip fracture morbidity, mortality and costs.J Am Geriatr Soc.2003;51:364–370. , , .
- The aging of America. Impact on health care costs.JAMA.1990;263:2335–2340. , .
- Medical expenditures for the treatment of osteoporotic fractures in the United States in 1995: report from the National Osteoporosis Foundation.J Bone Miner Res.1997;12(1):24–35. , , , .
- US Department of Health and Human Services.Surveillance for selected public health indicators affecting older adults —United States.MMWR Morb Mortal Wkly Rep1999;48:33–34.
- Epidemiology and outcomes of osteoporotic fractures.Lancet.2002;359:1761–1767. , .
- Effects of a hospitalist model on elderly patients with hip fracture.Arch Intern Med.2005;165:796–801. , , , et al.
- Hip fractures in Finland and Great Britain—a comparison of patient characteristics and outcomes.Int Orthop.2001;25:349–354. , , .
- WHO.International Classification of Disease, Ninth Revision (ICD‐9).Geneva, Switzerland:World Health Organization;1977.
- Medical and surgical comanagement after elective hip and knee arthroplasty: a randomized, controlled trial.Ann Intern Med.2004;141(1):28–38. , , , et al.
- Regression models and life‐tables (with discussion).J R Stat Soc Ser B.1972;34:187–220. .
- Nonparametric estimation from incomplete observations.J Am Statistical Assoc.1958;53:457–481. , .
- An Introduction to Recursive Partitioning using the RPART Routines: Section of Biostatistics, Mayo Clinic;1997. , .
- Computer Intensive Statistical Methods, Validation, Model Selection, and Bootstrap.London:Chapman and Hall;1994. .
- A bootstrap resampling procedure for model building: application to the Cox regression model.Stat Med.1992;11:2093–2109. , .
- Associations between the hospitalist model of care and quality‐of‐care‐related outcomes in patients undergoing hip fracture surgery.Mayo Clin Proc.2006;81(1):28–31. , , .
- Association of timing of surgery for hip fracture and patient outcomes.JAMA.2004;291:1738–1743. , , , et al.
- The effects of time‐to‐surgery on mortality and morbidity in patients following hip fracture.Am J Med.2002;112:702–709. , , , , .
- Morbidity and mortality after hip fracture: the impact of operative delay.Arch Orthop Trauma Surg.2004;124:334–340. , , , .
- Delay to surgery prolongs hospital stay in patients with fractures of the proximal femur.J Bone Joint Surg Br.2005;87:1123–1126. , , .
- The timing of surgery for proximal femoral fractures.J Bone Joint Surg Br.1992;74(2):203–205. , .
- Hospital readmissions after hospital discharge for hip fracture: surgical and nonsurgical causes and effect on outcomes.J Am Geriatr Soc.2003;51:399–403. , , , et al.
- Mortality after hip fractures.Acta Orthop Scand1979;50(2):161–167. , .
- Medical complications and outcomes after hip fracture repair.Arch Intern Med.2002;162:2053–2057. , , , , .
- Development and initial validation of a risk score for predicting in‐hospital and 1‐year mortality in patients with hip fractures.J Bone Miner Res.2005;20:494–500. , , , et al.
- Outcome after hip fracture in individuals ninety years of age and older.J Orthop Trauma.2001;15(1):34–39. , , , , .
- Hip fractures in the elderly: predictors of one year mortality.J Orthop Trauma.1997;11(3):162–165. , , , .
- The effect of hospital type and surgical delay on mortality after surgery for hip fracture.J Bone Joint Surg Br.2005;87:361–366. , , , .
- History of the Rochester Epidemiology Project.Mayo Clin Proc.1996;71:266–274. .
- The mortality and social prognosis of hip fractures. A prospective multifactorial study.Int Orthop.1994;18(2):109–113. .
- Functional outcome after hip fracture. A 1‐year prospective outcome study of 275 patients.Injury.2003;34:529–532. , .
- Rate of mortality for elderly patients after fracture of the hip in the 1980's.J Bone Joint Surg Am.1987;69:1335–1340. , , .
- Hip fractures in the elderly. Mortality, functional results and social readaptation.Int Surg.1989;74(3):191–194. , , , .
- Blood transfusion requirements in femoral neck fracture.Injury.2000;31(1):7–10. , , .
- Mortality and causes of death after hip fractures in The Netherlands.Neth J Med.1992;41(1–2):4–10. , , .
- Influence of preoperative medical status and delay to surgery on death following a hip fracture.ANZ J Surg.2002;72:405–407. , , .
- Predictors of mortality and institutionalization after hip fracture: the New Haven EPESE cohort. Established Populations for Epidemiologic Studies of the Elderly.Am J Public Health.1994;84:1807–1812. , , ,
- Mortality risk after hip fracture.J Orthop Trauma.2003;17(1):53–56. , , , .
- Thirty‐day mortality following hip arthroplasty for acute fracture.J Bone Joint Surg Am.2004;86‐A:1983–1988. , , .
- Functional outcomes and mortality vary among different types of hip fractures: a function of patient characteristics.Clin Orthop Relat Res.2004:64–71. , , , , .
- Implementation of a voluntary hospitalist service at a community teaching hospital: improved clinical efficiency and patient outcomes.Ann Intern Med.2002;137:859–865. , , , , , .
- Effects of physician experience on costs and outcomes on an academic general medicine service: results of a trial of hospitalists.Ann Intern Med.2002;137:866–874. , , , et al.
Because the incidence of hip fracture increases dramatically with age and the elderly are the fastest‐growing portion of the United States population, the number of hip fractures is expected to triple by 2040.1 With the associated increase in postoperative morbidity and mortality, the costs will likely exceed $16‐$20 billion annually.15 Already by 2002, the number of patients with hip fractures exceeded 340,000 in this country, resulting in $8.6 billion in health care expenditures from in‐hospital and posthospital costs.68 This makes hip fracture a serious public health concern and triggers a need to devise an efficient means of caring for these patients. We previously reported that a hospitalist service can decrease time to surgery and shorten length of stay without affecting the number of inpatient deaths or 30‐day readmissions of patients undergoing hip fracture surgery.9 However, one concern with reducing length of stay and time to surgery in the high‐risk hip fracture patient population is the effect on long‐term mortality because the death rate following hip fracture repair may be as high as 43% after 1 year.10 To evaluate this important issue, we assessed mortality over a 1‐year period in the same cohort of patients previously described.9 We also identified predictors associated with mortality. We hypothesized that the expedited surgical treatment and decreased length of stay of a hospitalist‐managed group would not have an adverse effect on 1‐year mortality.
METHODS
Patient Selection
Following approval by the Mayo Clinic Institutional Review Board, we used the Mayo Clinic Surgical Index to identify patients admitted between July 1, 2000, and June 30, 2002, who matched International Classification of Diseases (9th Edition) hip fracture codes.11 These patients were cross‐referenced with those having a primary surgical indication of hip fracture. Patients transferred to our facility more than 72 hours after fracture were excluded from our study. Study patients provided authorization to use their medical records for the purposes of research.
A cohort of 466 patients was identified. For purposes of comparison, patients admitted between July 1, 2000, and June 30, 2001, were deemed to belong to the standard care service, and patients admitted between July 1, 2001, and June 30, 2002, were deemed part of the hospitalist service.
Intervention
Prior to July 2001, Mayo Clinic patients aged 65 and older having surgical repair of a hip fracture were triaged directly to a surgical orthopedic or general medical teaching service. Patients with multiple medical diagnoses were managed initially on a medical teaching service prior to transfer to the operating room. The primary team (medical or surgical) was responsible for the postoperative care of the patient and any orders or consultations required.
After July 1, 2001, these patients were admitted by the orthopedic surgery service and medically comanaged by a hospitalist service, which consisted of a hospitalist physician and 2 allied‐health practitioners. Twelve hospitalists and 12 allied health care professionals cared for patients during the study period. All preoperative and postoperative evaluations, inpatient management decisions, and coordination of outpatient care were performed by the hospitalists. This model of care is similar to one previously studied and published elsewhere.12 A census cap of 20 patients limited the number of patients managed by the hospitalist service. Any overflow of hip fracture patients was triaged directly to a non‐hospitalist‐based primary medical or surgical service as before. Thus, 23 hip fracture patients (10%) admitted after July 1, 2001, were not managed by the hospitalists but are included in this group for an intent‐to‐treat analysis.
Data Collection
Study nurses abstracted all data including admitting diagnoses, demographic features, type and mechanism of hip fracture, admission date and time, American Society of Anesthesia (ASA) class, comorbid medical conditions, medications, all clinical data, and readmission rates. Date of last follow‐up was confirmed using the Mayo Clinic medical record, whereas date and cause of death were obtained from death certificates obtained from state and national sources. Length of stay was defined as the number of days between admission and discharge. Time to surgery was defined in hours as the time from hospital admission to the start of the surgery. Finally, time from surgery to dismissal was defined as the number of days from the initiation of the surgical procedure to the time of dismissal. Thirty‐day readmission was defined as readmission to our hospital within 30 days of discharge date.
Statistical Considerations
Power
The power analysis was based on the end point of survival following surgical repair of hip fracture and primary comparison of patients in the standard care group with those in the hospitalist group. With 236 patients in the standard care group, 230 in the hospitalist group, and 274 observed deaths during the follow‐up period, there was 80% power to detect a hazard ratio of 1.4 or greater as being statistically significant (alpha = 0.05, beta = 0.2).
Analysis
The analysis focused on the end point of survival following surgical repair of hip fracture. In addition to the hospitalist versus standard care service, demographic, baseline clinical, and in‐hospital data were evaluated as potential predictors of survival. Survival rates were estimated using the method of Kaplan and Meier, and relative differences in survival were evaluated using the Cox proportional hazards regression models.13, 14 Potential predictors were analyzed both univariately and in a multivariable model. For the multivariable model, initial variable selection was accomplished using stepwise selection, backward elimination, and recursive partitioning.15 Each method yielded similar results. Bootstrap resampling was then used to confirm the variables selected for each model.16, 17 The threshold of statistical significance was set at P = .05 for all tests. All analyses were conducted in SAS version 8.2 (SAS Institute Inc., Cary, NC) and Splus version 6.2.1 (Insightful Corporation, Seattle, WA).
RESULTS
There were 236 patients with hip fractures (50.6%) admitted to the standard care service, and 230 patients (49.4%) admitted to the hospitalist service. As shown in Table 1, the baseline characteristics of the patients admitted to the 2 services did not differ significantly except that a greater proportion of patients with hypoxia were admitted to the hospitalist service (11.3% vs. 5.5%; P = .02). However, time to surgery, postsurgery stay, and overall length of hospitalization of the hospitalist‐treated patients were all significantly shorter.
Patient characteristic | Standard care n = 236 | Hospitalist care n = 230 | P value | ||
---|---|---|---|---|---|
| |||||
Age (years) | 82 | 83 | .34 | ||
Female sex | 171 | 72.5% | 163 | 70.9% | .70 |
Comorbidity | |||||
Coronary artery disease | 69 | 29.2% | 77 | 33.5% | .32 |
Congestive heart failure | 41 | 17.4% | 49 | 21.3% | .28 |
Chronic obstructive pulmonary disease | 36 | 15.3% | 38 | 16.5% | .71 |
Cerebral vascular accident or transient ischemic attack | 36 | 15.3% | 50 | 21.7% | .07 |
Dementia | 54 | 22.9% | 62 | 27.0% | .31 |
Diabetes | 45 | 19.1% | 46 | 20.0% | .80 |
Renal insufficiency | 17 | 7.2% | 17 | 7.4% | .94 |
Residence at time of admission | .07 | ||||
Home | 149 | 63.1% | 138 | 60.0% | |
Assisted living | 32 | 13.6% | 42 | 18.3% | |
Nursing home | 55 | 23.3% | 50 | 21.7% | |
Ambulatory status at time of admission | .14 | ||||
Independent | 114 | 48.3% | 89 | 38.7% | |
Assistive device | 99 | 41.9% | 115 | 50.0% | |
Personal help | 9 | 3.8% | 16 | 7.0% | |
Transfer to bed or chair | 9 | 3.8% | 7 | 3.0% | |
Nonambulatory | 5 | 2.1% | 3 | 1.3% | |
Signs at time of admission | |||||
Hypotension | 4 | 1.7% | 3 | 1.3% | > .99 |
Hypoxia | 13 | 5.5% | 26 | 11.3% | .02 |
Pulmonary edema | 37 | 15.7% | 29 | 12.6% | .34 |
Tachycardia | 19 | 8.1% | 25 | 10.9% | .3 |
Fracture type | .78 | ||||
Femoral neck | 118 | 50.0% | 118 | 51.3% | |
Intertrochanteric | 118 | 50.0% | 112 | 48.7% | |
Mechanism of fracture | .82 | ||||
Fall | 219 | 92.8% | 212 | 92.2% | |
Trauma | 1 | 0.4% | 3 | 1.3% | |
Pathologic | 7 | 3.0% | 6 | 2.6% | |
Unknown | 9 | 3.8% | 7 | 3.0% | |
ASA* class | .38 | ||||
I or II | 33 | 14.0% | 23 | 10.0% | |
III | 166 | 70.3% | 166 | 72.2% | |
IV | 37 | 15.7% | 41 | 17.8% | |
Location discharged to | .07 | ||||
Home or assisted living | 24 | 10.5% | 13 | 5.9% | |
Nursing home | 196 | 86.0% | 192 | 87.3% | |
Another hospital or hospice | 8 | 3.5% | 15 | 6.8% | |
Time to surgery (hours) | 38 | 25 | .001 | ||
Time from surgery to discharge (days) | 9 | 7 | .04 | ||
Length of stay | 10.6 | 8.4 | < .00 | ||
Readmission rate | 25 | 10.6% | 20 | 8.7% | .49 |
Patients were followed for a median of 4.0 years (range 5 days to 5.6 years), and 192 patients were still alive at the end of follow‐up (April 2006). As illustrated in Figure 1, survival did not differ between the 2 treatment groups (P = .36). Overall survival at 1 year was 70.6% (95% confidence interval [CI]: 66.5%, 74.9%). Survival at 1 year in the standard care group was 70.6% (95% CI: 64.9%, 76.8%), whereas in the hospitalist group, it was 70.5% (95% CI: 64.8%, 76.7%). As delineated in Table 2, cardiovascular causes accounted for 34 deaths (25.6%), with 14 of these in the standard care group and 20 in the hospitalist group; 29 deaths (21.8%) had respiratory causes, 20 in the standard care group and 9 in the hospitalist group; and 17 (12.8%) were due to cancer, with 7 and 10 in the standard care and hospitalist groups, respectively. Unknown causes accounted for 21 cases, or 15.8% of total deaths.
Standard care | Hospitalist care | Total No. of deaths | % | |
---|---|---|---|---|
Cancer | 7 | 10 | 17 | 12.8% |
Cardiovascular | 14 | 20 | 34 | 25.6% |
Infectious | 5 | 4 | 9 | 6.8% |
Neurological | 5 | 10 | 15 | 11.3% |
Other | 0 | 2 | 2 | 1.5% |
Renal | 4 | 2 | 6 | 4.5% |
Respiratory | 20 | 9 | 29 | 21.8% |
Unknown | 11 | 10 | 21 | 15.8% |
Total | 66 | 67 | 133 | 100.0% |
In the univariate analysis, we found 29 variables that were significant predictors of survival (Table 3). A hospitalist model of care was not significantly associated with patient survival, despite the shorter length of stay (8.4 days vs. 10.6 days; P < .001) or expedited time to surgery (25 vs. 38 hours; P < .001), when compared with the standard care group, as previously reported by Phy et al.9 In the multivariable analysis (Table 4), however, the independent predictors of mortality were ASA class III or IV versus class II (hazard ratio [HR] 4.20; 95% CI: 2.21, 7.99), admission from a nursing home versus from home or assisted living (HR 2.24; 95% CI: 1.73, 2.90), and inpatient complications, which included patients requiring admission to the intensive care unit (ICU) and those who had a myocardial infarction or acute renal failure as an inpatient (HR 1.85; 95% CI: 1.45, 2.35). Even after adjusting for these factors, survival following hip fracture did not differ significantly between the hospitalist care patients and the standard care patients (HR 1.16; 95% CI: 0.91, 1.48).
Variable | Hazard ratio (95% CI) | P value |
---|---|---|
| ||
Age on admission per 10 years | 1.41 (1.20, 1.65) | < .001 |
ASA* II | 1.0 (referent) | |
ASA* III | 5.27 (2.79, 9.96) | < .001 |
ASA* IV | 11.7 (5.97, 22.9) | < .001 |
History of chronic obstructive pulmonary disease | 1.82 (1.35, 2.43) | < .001 |
History of renal insufficiency | 2.40 (1.62,3.55) | < .001 |
History of stroke/transient ischemic attack | 1.46 (1.10, 1.95) | .01 |
History of diabetes | 1.70 (1.29,2.25) | < .001 |
History of congestive heart failure | 2.26 (1.73, 2.96) | < .001 |
History of coronary artery disease | 1.53 (1.20, 1.97) | < .001 |
History of dementia | 2.02 (1.57, 2.59) | < .001 |
Admission from home | 1.0 (referent) | |
Admission from assisted living | 1.47 (1.06, 2.04) | .02 |
Admission from nursing home | 3.04 (2.33, 3.98) | < .001 |
Independent | 1.0 (referent) | |
Use of assistive device | 1.81 (1.39, 2.36) | < .001 |
Personal help | 3.49 (2.16, 5.64) | < .001 |
Nonambulatory | 3.96 (2.47, 6.35) | < .001 |
Crackles on admission | 2.03 (1.50, 2.74) | < .001 |
Hypoxia on admission | 1.56 (1.04, 2.32) | .03 |
Hypotension on admission | 6.21 (2.72, 14.2) | < .001 |
Tachycardia on admission | 1.66 (1.15, 2.41) | .007 |
Coumadin on admission | 1.57 (1.13, 2.18) | .007 |
Confusion/unconsciousness on admission | 2.23 (1.74, 2.87) | < .001 |
Fever on admission | 1.98 (1.16, 3.40) | .01 |
Tachypnea on admission | 1.95 (1.39, 2.72) | < .001 |
Inpatient myocardial Infarction | 3.59 (2.35, 5.48) | < .001 |
Inpatient atrial fibrillation | 2.00 (1.37, 2.92) | < .001 |
Inpatient congestive heart failure | 2.62 (1.79, 3.84) | < .0001 |
Inpatient delirium | 1.46 (1.13, 1.90) | < .005 |
Inpatient lung infection | 2.52 (1.85, 3.42) | < .001 |
Inpatient respiratory failure | 2.76 (1.64, 4.66) | < .001 |
Inpatient mechanical ventilation | 2.56 (1.43, 4.57) | .002 |
Inpatient renal failure | 3.60 (1.97, 6.61) | < .001 |
Days from admission to surgery | 1.06 (1.005, 1.12) | .03 |
Intensive care unit stay | 1.93 (1.51, 2.47) | < .001 |
Variable | Hazard ratio (95% CI) | P value |
---|---|---|
| ||
Age on admission per 10 years | 1.17 (0.99, 1.38) | .07 |
ASA* class III or IV | 4.20 (2.21, 7.99) | < .001 |
ASA* class II | 1.0 (referent) | |
Admission from nursing home | 2.24 (1.73, 2.90) | < .001 |
Admission from home or assisted living | 1.0 (referent) | |
Inpatient myocardial infarction, inpatient acute renal failure, or intensive care unit stay | 1.85 (1.45, 2.35) | < .001 |
No inpatient myocardial infarction, no inpatient acute renal failure, and no intensive care unit stay | 1.0 (referent) |
DISCUSSION
In our previous study, length of stay and time to surgery were significantly lower in a hospitalist care model.9 The present study shows that neither the reduced length of stay nor the shortened time to surgery of patients managed by the hospitalist group was associated with a difference in mortality compared with a standard care group, despite significantly improved efficiency and processes of care. Thus, our results refute initial concerns of increased mortality in a hospitalist model of care.
Delivery of perioperative medical care to hip fracture patients by hospitalists is associated with significant decreases in time to surgery and length of stay compared with standard care, with no differences in short‐term mortality.9, 18 Although there have been conflicting reports on the impact of length of stay and time to surgery on long‐term outcomes, our findings support previous results that decreased time to surgery was not associated with an observable effect on mortality.1923 A recent study by Orosz et al. that evaluated 1178 patients showed that earlier hip fracture surgery (performed less than 24 hours after admission) was not associated with reduced mortality, although it was associated with shorter length of stay.19 Our study also corroborates the results of an examination of 8383 hip fracture patients by Grimes et al., who found that time to surgery between 24 and 48 hours after admission had no effect on either 30‐day or long‐term mortality compared with that of those who underwent surgery between 48 and 72 hours, between 72 and 96 hours, or more than 96 hours after admission.20 However, both these results and our own are contrary to those of Gdalevich, whose study of 651 patients found that 1‐year mortality was 1.6‐fold higher for those whose hip fracture repair was postponed more than 48 hours.21 However, time to surgery in both the standard care and hospitalist model in our study was well below the 48‐hour cutoff, suggesting that operating anywhere within the normally accepted 48‐hour time frame may not influence long‐term mortality.
Because of the small number of events in both groups, we were unable to specifically compare whether a hospitalist model of care has any specific impact on long‐term cause of death. Although causes of death of patients with hip fracture were consistent with those of previous studies,10, 24 our death rate at 1 year, 29.4%, was higher than that seen among similar population groups at tertiary referral centers.19, 20, 2429 This is most likely a result of the cohort having a high proportion of nursing home patients (22%)19, 24, 26 transferred for evaluation to St. Mary's Hospital, which serves most of Olmsted County, Minnesota. This hospital also has some characteristics of a community‐based hospital, as it is where greater than 95% of all county patients receive care for surgical repair of hip fracture. Mortality rates are often higher at these types of hospitals.30 Previous studies using patients from Olmsted County indicate results can also be extrapolated to a large part of the U.S. population.31 In Pitto et al.'s study, the risk of death was 31% lower in those admitted from home than for those admitted from a nursing home.32 The latter patients normally have a higher number of comorbid conditions and tend to be less ambulatory than those in a community home‐dwelling setting. Our study also demonstrated that admission from a nursing home was a strong predictor of mortality for up to 1 year in the geriatric population. This may reflect the inherent decreased survival in this patient group, which is in agreement with the findings of other studies that showed inactivity and decreased ambulation prior to fracture were associated with increased mortality.3335
Multiple comorbidities, commonly seen in a geriatric population, translate into a higher ASA class and an increased risk of significant in‐hospital complications. Our study confirmed the findings of previous studies that a higher ASA class is a strong predictor of mortality,21, 26, 30, 3537 independent of decreased time to surgery.38 We also noted that significant in‐hospital complications, including renal failure, respiratory failure, and myocardial infarction, are documented predictors of mortality after hip fracture.27 Although mortality may vary depending on fracture type (femoral neck vs. intertrochanteric),3941 these differences were not observed in our study, in line with the results of previous published studies.37, 42 Controlling for age and comorbidities may be why an association was not found between fracture type and mortality. Finally, in a model containing comorbidity, ASA class, and nursing home residence prior to fracture, age was not a significant predictor of mortality.
Our study had a number of limitations. First, this was a retrospective cohort study based on chart review, so some data may have been subject to recording bias, and this might have differed between the serial models. Because of the retrospective nature of the study and referral of some of the patients from outside the community, our 1‐year follow‐up was not complete, but approached a respectable 93%. Other studies have described the benefits derived by a hospitalist practice only following the first year of its implementation, likely because of the hospitalist learning curve.43, 44 This may be why there was no difference in mortality between the standard care and hospitalist groups, as the latter was only in its first year of existence. Additional longitudinal study is required to find out if mortality differences emerge between the treatment groups. Furthermore, although in‐hospital care may influence short‐term outcomes, its effect on long‐term mortality has been unclear. Our data demonstrate that even though a hospitalist service can shorten length of stay and time to surgery, there were no appreciable intermediate differences in mortality at 1 year. Further prospective studies are needed to determine whether this medical‐surgical partnership in caring for these patients provides more favorable outcomes of reducing mortality and intercurrent complications.
Acknowledgements
We thank Donna K. Lawson for her assistance in data collection and management.
Because the incidence of hip fracture increases dramatically with age and the elderly are the fastest‐growing portion of the United States population, the number of hip fractures is expected to triple by 2040.1 With the associated increase in postoperative morbidity and mortality, the costs will likely exceed $16‐$20 billion annually.15 Already by 2002, the number of patients with hip fractures exceeded 340,000 in this country, resulting in $8.6 billion in health care expenditures from in‐hospital and posthospital costs.68 This makes hip fracture a serious public health concern and triggers a need to devise an efficient means of caring for these patients. We previously reported that a hospitalist service can decrease time to surgery and shorten length of stay without affecting the number of inpatient deaths or 30‐day readmissions of patients undergoing hip fracture surgery.9 However, one concern with reducing length of stay and time to surgery in the high‐risk hip fracture patient population is the effect on long‐term mortality because the death rate following hip fracture repair may be as high as 43% after 1 year.10 To evaluate this important issue, we assessed mortality over a 1‐year period in the same cohort of patients previously described.9 We also identified predictors associated with mortality. We hypothesized that the expedited surgical treatment and decreased length of stay of a hospitalist‐managed group would not have an adverse effect on 1‐year mortality.
METHODS
Patient Selection
Following approval by the Mayo Clinic Institutional Review Board, we used the Mayo Clinic Surgical Index to identify patients admitted between July 1, 2000, and June 30, 2002, who matched International Classification of Diseases (9th Edition) hip fracture codes.11 These patients were cross‐referenced with those having a primary surgical indication of hip fracture. Patients transferred to our facility more than 72 hours after fracture were excluded from our study. Study patients provided authorization to use their medical records for the purposes of research.
A cohort of 466 patients was identified. For purposes of comparison, patients admitted between July 1, 2000, and June 30, 2001, were deemed to belong to the standard care service, and patients admitted between July 1, 2001, and June 30, 2002, were deemed part of the hospitalist service.
Intervention
Prior to July 2001, Mayo Clinic patients aged 65 and older having surgical repair of a hip fracture were triaged directly to a surgical orthopedic or general medical teaching service. Patients with multiple medical diagnoses were managed initially on a medical teaching service prior to transfer to the operating room. The primary team (medical or surgical) was responsible for the postoperative care of the patient and any orders or consultations required.
After July 1, 2001, these patients were admitted by the orthopedic surgery service and medically comanaged by a hospitalist service, which consisted of a hospitalist physician and 2 allied‐health practitioners. Twelve hospitalists and 12 allied health care professionals cared for patients during the study period. All preoperative and postoperative evaluations, inpatient management decisions, and coordination of outpatient care were performed by the hospitalists. This model of care is similar to one previously studied and published elsewhere.12 A census cap of 20 patients limited the number of patients managed by the hospitalist service. Any overflow of hip fracture patients was triaged directly to a non‐hospitalist‐based primary medical or surgical service as before. Thus, 23 hip fracture patients (10%) admitted after July 1, 2001, were not managed by the hospitalists but are included in this group for an intent‐to‐treat analysis.
Data Collection
Study nurses abstracted all data including admitting diagnoses, demographic features, type and mechanism of hip fracture, admission date and time, American Society of Anesthesia (ASA) class, comorbid medical conditions, medications, all clinical data, and readmission rates. Date of last follow‐up was confirmed using the Mayo Clinic medical record, whereas date and cause of death were obtained from death certificates obtained from state and national sources. Length of stay was defined as the number of days between admission and discharge. Time to surgery was defined in hours as the time from hospital admission to the start of the surgery. Finally, time from surgery to dismissal was defined as the number of days from the initiation of the surgical procedure to the time of dismissal. Thirty‐day readmission was defined as readmission to our hospital within 30 days of discharge date.
Statistical Considerations
Power
The power analysis was based on the end point of survival following surgical repair of hip fracture and primary comparison of patients in the standard care group with those in the hospitalist group. With 236 patients in the standard care group, 230 in the hospitalist group, and 274 observed deaths during the follow‐up period, there was 80% power to detect a hazard ratio of 1.4 or greater as being statistically significant (alpha = 0.05, beta = 0.2).
Analysis
The analysis focused on the end point of survival following surgical repair of hip fracture. In addition to the hospitalist versus standard care service, demographic, baseline clinical, and in‐hospital data were evaluated as potential predictors of survival. Survival rates were estimated using the method of Kaplan and Meier, and relative differences in survival were evaluated using the Cox proportional hazards regression models.13, 14 Potential predictors were analyzed both univariately and in a multivariable model. For the multivariable model, initial variable selection was accomplished using stepwise selection, backward elimination, and recursive partitioning.15 Each method yielded similar results. Bootstrap resampling was then used to confirm the variables selected for each model.16, 17 The threshold of statistical significance was set at P = .05 for all tests. All analyses were conducted in SAS version 8.2 (SAS Institute Inc., Cary, NC) and Splus version 6.2.1 (Insightful Corporation, Seattle, WA).
RESULTS
There were 236 patients with hip fractures (50.6%) admitted to the standard care service, and 230 patients (49.4%) admitted to the hospitalist service. As shown in Table 1, the baseline characteristics of the patients admitted to the 2 services did not differ significantly except that a greater proportion of patients with hypoxia were admitted to the hospitalist service (11.3% vs. 5.5%; P = .02). However, time to surgery, postsurgery stay, and overall length of hospitalization of the hospitalist‐treated patients were all significantly shorter.
Patient characteristic | Standard care n = 236 | Hospitalist care n = 230 | P value | ||
---|---|---|---|---|---|
| |||||
Age (years) | 82 | 83 | .34 | ||
Female sex | 171 | 72.5% | 163 | 70.9% | .70 |
Comorbidity | |||||
Coronary artery disease | 69 | 29.2% | 77 | 33.5% | .32 |
Congestive heart failure | 41 | 17.4% | 49 | 21.3% | .28 |
Chronic obstructive pulmonary disease | 36 | 15.3% | 38 | 16.5% | .71 |
Cerebral vascular accident or transient ischemic attack | 36 | 15.3% | 50 | 21.7% | .07 |
Dementia | 54 | 22.9% | 62 | 27.0% | .31 |
Diabetes | 45 | 19.1% | 46 | 20.0% | .80 |
Renal insufficiency | 17 | 7.2% | 17 | 7.4% | .94 |
Residence at time of admission | .07 | ||||
Home | 149 | 63.1% | 138 | 60.0% | |
Assisted living | 32 | 13.6% | 42 | 18.3% | |
Nursing home | 55 | 23.3% | 50 | 21.7% | |
Ambulatory status at time of admission | .14 | ||||
Independent | 114 | 48.3% | 89 | 38.7% | |
Assistive device | 99 | 41.9% | 115 | 50.0% | |
Personal help | 9 | 3.8% | 16 | 7.0% | |
Transfer to bed or chair | 9 | 3.8% | 7 | 3.0% | |
Nonambulatory | 5 | 2.1% | 3 | 1.3% | |
Signs at time of admission | |||||
Hypotension | 4 | 1.7% | 3 | 1.3% | > .99 |
Hypoxia | 13 | 5.5% | 26 | 11.3% | .02 |
Pulmonary edema | 37 | 15.7% | 29 | 12.6% | .34 |
Tachycardia | 19 | 8.1% | 25 | 10.9% | .3 |
Fracture type | .78 | ||||
Femoral neck | 118 | 50.0% | 118 | 51.3% | |
Intertrochanteric | 118 | 50.0% | 112 | 48.7% | |
Mechanism of fracture | .82 | ||||
Fall | 219 | 92.8% | 212 | 92.2% | |
Trauma | 1 | 0.4% | 3 | 1.3% | |
Pathologic | 7 | 3.0% | 6 | 2.6% | |
Unknown | 9 | 3.8% | 7 | 3.0% | |
ASA* class | .38 | ||||
I or II | 33 | 14.0% | 23 | 10.0% | |
III | 166 | 70.3% | 166 | 72.2% | |
IV | 37 | 15.7% | 41 | 17.8% | |
Location discharged to | .07 | ||||
Home or assisted living | 24 | 10.5% | 13 | 5.9% | |
Nursing home | 196 | 86.0% | 192 | 87.3% | |
Another hospital or hospice | 8 | 3.5% | 15 | 6.8% | |
Time to surgery (hours) | 38 | 25 | .001 | ||
Time from surgery to discharge (days) | 9 | 7 | .04 | ||
Length of stay | 10.6 | 8.4 | < .00 | ||
Readmission rate | 25 | 10.6% | 20 | 8.7% | .49 |
Patients were followed for a median of 4.0 years (range 5 days to 5.6 years), and 192 patients were still alive at the end of follow‐up (April 2006). As illustrated in Figure 1, survival did not differ between the 2 treatment groups (P = .36). Overall survival at 1 year was 70.6% (95% confidence interval [CI]: 66.5%, 74.9%). Survival at 1 year in the standard care group was 70.6% (95% CI: 64.9%, 76.8%), whereas in the hospitalist group, it was 70.5% (95% CI: 64.8%, 76.7%). As delineated in Table 2, cardiovascular causes accounted for 34 deaths (25.6%), with 14 of these in the standard care group and 20 in the hospitalist group; 29 deaths (21.8%) had respiratory causes, 20 in the standard care group and 9 in the hospitalist group; and 17 (12.8%) were due to cancer, with 7 and 10 in the standard care and hospitalist groups, respectively. Unknown causes accounted for 21 cases, or 15.8% of total deaths.
Standard care | Hospitalist care | Total No. of deaths | % | |
---|---|---|---|---|
Cancer | 7 | 10 | 17 | 12.8% |
Cardiovascular | 14 | 20 | 34 | 25.6% |
Infectious | 5 | 4 | 9 | 6.8% |
Neurological | 5 | 10 | 15 | 11.3% |
Other | 0 | 2 | 2 | 1.5% |
Renal | 4 | 2 | 6 | 4.5% |
Respiratory | 20 | 9 | 29 | 21.8% |
Unknown | 11 | 10 | 21 | 15.8% |
Total | 66 | 67 | 133 | 100.0% |
In the univariate analysis, we found 29 variables that were significant predictors of survival (Table 3). A hospitalist model of care was not significantly associated with patient survival, despite the shorter length of stay (8.4 days vs. 10.6 days; P < .001) or expedited time to surgery (25 vs. 38 hours; P < .001), when compared with the standard care group, as previously reported by Phy et al.9 In the multivariable analysis (Table 4), however, the independent predictors of mortality were ASA class III or IV versus class II (hazard ratio [HR] 4.20; 95% CI: 2.21, 7.99), admission from a nursing home versus from home or assisted living (HR 2.24; 95% CI: 1.73, 2.90), and inpatient complications, which included patients requiring admission to the intensive care unit (ICU) and those who had a myocardial infarction or acute renal failure as an inpatient (HR 1.85; 95% CI: 1.45, 2.35). Even after adjusting for these factors, survival following hip fracture did not differ significantly between the hospitalist care patients and the standard care patients (HR 1.16; 95% CI: 0.91, 1.48).
Variable | Hazard ratio (95% CI) | P value |
---|---|---|
| ||
Age on admission per 10 years | 1.41 (1.20, 1.65) | < .001 |
ASA* II | 1.0 (referent) | |
ASA* III | 5.27 (2.79, 9.96) | < .001 |
ASA* IV | 11.7 (5.97, 22.9) | < .001 |
History of chronic obstructive pulmonary disease | 1.82 (1.35, 2.43) | < .001 |
History of renal insufficiency | 2.40 (1.62,3.55) | < .001 |
History of stroke/transient ischemic attack | 1.46 (1.10, 1.95) | .01 |
History of diabetes | 1.70 (1.29,2.25) | < .001 |
History of congestive heart failure | 2.26 (1.73, 2.96) | < .001 |
History of coronary artery disease | 1.53 (1.20, 1.97) | < .001 |
History of dementia | 2.02 (1.57, 2.59) | < .001 |
Admission from home | 1.0 (referent) | |
Admission from assisted living | 1.47 (1.06, 2.04) | .02 |
Admission from nursing home | 3.04 (2.33, 3.98) | < .001 |
Independent | 1.0 (referent) | |
Use of assistive device | 1.81 (1.39, 2.36) | < .001 |
Personal help | 3.49 (2.16, 5.64) | < .001 |
Nonambulatory | 3.96 (2.47, 6.35) | < .001 |
Crackles on admission | 2.03 (1.50, 2.74) | < .001 |
Hypoxia on admission | 1.56 (1.04, 2.32) | .03 |
Hypotension on admission | 6.21 (2.72, 14.2) | < .001 |
Tachycardia on admission | 1.66 (1.15, 2.41) | .007 |
Coumadin on admission | 1.57 (1.13, 2.18) | .007 |
Confusion/unconsciousness on admission | 2.23 (1.74, 2.87) | < .001 |
Fever on admission | 1.98 (1.16, 3.40) | .01 |
Tachypnea on admission | 1.95 (1.39, 2.72) | < .001 |
Inpatient myocardial Infarction | 3.59 (2.35, 5.48) | < .001 |
Inpatient atrial fibrillation | 2.00 (1.37, 2.92) | < .001 |
Inpatient congestive heart failure | 2.62 (1.79, 3.84) | < .0001 |
Inpatient delirium | 1.46 (1.13, 1.90) | < .005 |
Inpatient lung infection | 2.52 (1.85, 3.42) | < .001 |
Inpatient respiratory failure | 2.76 (1.64, 4.66) | < .001 |
Inpatient mechanical ventilation | 2.56 (1.43, 4.57) | .002 |
Inpatient renal failure | 3.60 (1.97, 6.61) | < .001 |
Days from admission to surgery | 1.06 (1.005, 1.12) | .03 |
Intensive care unit stay | 1.93 (1.51, 2.47) | < .001 |
Variable | Hazard ratio (95% CI) | P value |
---|---|---|
| ||
Age on admission per 10 years | 1.17 (0.99, 1.38) | .07 |
ASA* class III or IV | 4.20 (2.21, 7.99) | < .001 |
ASA* class II | 1.0 (referent) | |
Admission from nursing home | 2.24 (1.73, 2.90) | < .001 |
Admission from home or assisted living | 1.0 (referent) | |
Inpatient myocardial infarction, inpatient acute renal failure, or intensive care unit stay | 1.85 (1.45, 2.35) | < .001 |
No inpatient myocardial infarction, no inpatient acute renal failure, and no intensive care unit stay | 1.0 (referent) |
DISCUSSION
In our previous study, length of stay and time to surgery were significantly lower in a hospitalist care model.9 The present study shows that neither the reduced length of stay nor the shortened time to surgery of patients managed by the hospitalist group was associated with a difference in mortality compared with a standard care group, despite significantly improved efficiency and processes of care. Thus, our results refute initial concerns of increased mortality in a hospitalist model of care.
Delivery of perioperative medical care to hip fracture patients by hospitalists is associated with significant decreases in time to surgery and length of stay compared with standard care, with no differences in short‐term mortality.9, 18 Although there have been conflicting reports on the impact of length of stay and time to surgery on long‐term outcomes, our findings support previous results that decreased time to surgery was not associated with an observable effect on mortality.1923 A recent study by Orosz et al. that evaluated 1178 patients showed that earlier hip fracture surgery (performed less than 24 hours after admission) was not associated with reduced mortality, although it was associated with shorter length of stay.19 Our study also corroborates the results of an examination of 8383 hip fracture patients by Grimes et al., who found that time to surgery between 24 and 48 hours after admission had no effect on either 30‐day or long‐term mortality compared with that of those who underwent surgery between 48 and 72 hours, between 72 and 96 hours, or more than 96 hours after admission.20 However, both these results and our own are contrary to those of Gdalevich, whose study of 651 patients found that 1‐year mortality was 1.6‐fold higher for those whose hip fracture repair was postponed more than 48 hours.21 However, time to surgery in both the standard care and hospitalist model in our study was well below the 48‐hour cutoff, suggesting that operating anywhere within the normally accepted 48‐hour time frame may not influence long‐term mortality.
Because of the small number of events in both groups, we were unable to specifically compare whether a hospitalist model of care has any specific impact on long‐term cause of death. Although causes of death of patients with hip fracture were consistent with those of previous studies,10, 24 our death rate at 1 year, 29.4%, was higher than that seen among similar population groups at tertiary referral centers.19, 20, 2429 This is most likely a result of the cohort having a high proportion of nursing home patients (22%)19, 24, 26 transferred for evaluation to St. Mary's Hospital, which serves most of Olmsted County, Minnesota. This hospital also has some characteristics of a community‐based hospital, as it is where greater than 95% of all county patients receive care for surgical repair of hip fracture. Mortality rates are often higher at these types of hospitals.30 Previous studies using patients from Olmsted County indicate results can also be extrapolated to a large part of the U.S. population.31 In Pitto et al.'s study, the risk of death was 31% lower in those admitted from home than for those admitted from a nursing home.32 The latter patients normally have a higher number of comorbid conditions and tend to be less ambulatory than those in a community home‐dwelling setting. Our study also demonstrated that admission from a nursing home was a strong predictor of mortality for up to 1 year in the geriatric population. This may reflect the inherent decreased survival in this patient group, which is in agreement with the findings of other studies that showed inactivity and decreased ambulation prior to fracture were associated with increased mortality.3335
Multiple comorbidities, commonly seen in a geriatric population, translate into a higher ASA class and an increased risk of significant in‐hospital complications. Our study confirmed the findings of previous studies that a higher ASA class is a strong predictor of mortality,21, 26, 30, 3537 independent of decreased time to surgery.38 We also noted that significant in‐hospital complications, including renal failure, respiratory failure, and myocardial infarction, are documented predictors of mortality after hip fracture.27 Although mortality may vary depending on fracture type (femoral neck vs. intertrochanteric),3941 these differences were not observed in our study, in line with the results of previous published studies.37, 42 Controlling for age and comorbidities may be why an association was not found between fracture type and mortality. Finally, in a model containing comorbidity, ASA class, and nursing home residence prior to fracture, age was not a significant predictor of mortality.
Our study had a number of limitations. First, this was a retrospective cohort study based on chart review, so some data may have been subject to recording bias, and this might have differed between the serial models. Because of the retrospective nature of the study and referral of some of the patients from outside the community, our 1‐year follow‐up was not complete, but approached a respectable 93%. Other studies have described the benefits derived by a hospitalist practice only following the first year of its implementation, likely because of the hospitalist learning curve.43, 44 This may be why there was no difference in mortality between the standard care and hospitalist groups, as the latter was only in its first year of existence. Additional longitudinal study is required to find out if mortality differences emerge between the treatment groups. Furthermore, although in‐hospital care may influence short‐term outcomes, its effect on long‐term mortality has been unclear. Our data demonstrate that even though a hospitalist service can shorten length of stay and time to surgery, there were no appreciable intermediate differences in mortality at 1 year. Further prospective studies are needed to determine whether this medical‐surgical partnership in caring for these patients provides more favorable outcomes of reducing mortality and intercurrent complications.
Acknowledgements
We thank Donna K. Lawson for her assistance in data collection and management.
- The future of hip fractures in the United States. Numbers, costs, and potential effects of postmenopausal estrogen.Clin Orthop Relat Res1990 (252):163–166. , , .
- Hip fractures in the elderly: a world‐wide projection.Osteoporos Int.1992;2:285–289. , , .
- The economic cost of hip fractures among elderly women. A one‐year, prospective, observational cohort study with matched‐pair analysis.Belgian Hip Fracture Study Group.J Bone Joint Surg Am.2001;83‐A:493–500. , , , .
- Estimating hip fracture morbidity, mortality and costs.J Am Geriatr Soc.2003;51:364–370. , , .
- The aging of America. Impact on health care costs.JAMA.1990;263:2335–2340. , .
- Medical expenditures for the treatment of osteoporotic fractures in the United States in 1995: report from the National Osteoporosis Foundation.J Bone Miner Res.1997;12(1):24–35. , , , .
- US Department of Health and Human Services.Surveillance for selected public health indicators affecting older adults —United States.MMWR Morb Mortal Wkly Rep1999;48:33–34.
- Epidemiology and outcomes of osteoporotic fractures.Lancet.2002;359:1761–1767. , .
- Effects of a hospitalist model on elderly patients with hip fracture.Arch Intern Med.2005;165:796–801. , , , et al.
- Hip fractures in Finland and Great Britain—a comparison of patient characteristics and outcomes.Int Orthop.2001;25:349–354. , , .
- WHO.International Classification of Disease, Ninth Revision (ICD‐9).Geneva, Switzerland:World Health Organization;1977.
- Medical and surgical comanagement after elective hip and knee arthroplasty: a randomized, controlled trial.Ann Intern Med.2004;141(1):28–38. , , , et al.
- Regression models and life‐tables (with discussion).J R Stat Soc Ser B.1972;34:187–220. .
- Nonparametric estimation from incomplete observations.J Am Statistical Assoc.1958;53:457–481. , .
- An Introduction to Recursive Partitioning using the RPART Routines: Section of Biostatistics, Mayo Clinic;1997. , .
- Computer Intensive Statistical Methods, Validation, Model Selection, and Bootstrap.London:Chapman and Hall;1994. .
- A bootstrap resampling procedure for model building: application to the Cox regression model.Stat Med.1992;11:2093–2109. , .
- Associations between the hospitalist model of care and quality‐of‐care‐related outcomes in patients undergoing hip fracture surgery.Mayo Clin Proc.2006;81(1):28–31. , , .
- Association of timing of surgery for hip fracture and patient outcomes.JAMA.2004;291:1738–1743. , , , et al.
- The effects of time‐to‐surgery on mortality and morbidity in patients following hip fracture.Am J Med.2002;112:702–709. , , , , .
- Morbidity and mortality after hip fracture: the impact of operative delay.Arch Orthop Trauma Surg.2004;124:334–340. , , , .
- Delay to surgery prolongs hospital stay in patients with fractures of the proximal femur.J Bone Joint Surg Br.2005;87:1123–1126. , , .
- The timing of surgery for proximal femoral fractures.J Bone Joint Surg Br.1992;74(2):203–205. , .
- Hospital readmissions after hospital discharge for hip fracture: surgical and nonsurgical causes and effect on outcomes.J Am Geriatr Soc.2003;51:399–403. , , , et al.
- Mortality after hip fractures.Acta Orthop Scand1979;50(2):161–167. , .
- Medical complications and outcomes after hip fracture repair.Arch Intern Med.2002;162:2053–2057. , , , , .
- Development and initial validation of a risk score for predicting in‐hospital and 1‐year mortality in patients with hip fractures.J Bone Miner Res.2005;20:494–500. , , , et al.
- Outcome after hip fracture in individuals ninety years of age and older.J Orthop Trauma.2001;15(1):34–39. , , , , .
- Hip fractures in the elderly: predictors of one year mortality.J Orthop Trauma.1997;11(3):162–165. , , , .
- The effect of hospital type and surgical delay on mortality after surgery for hip fracture.J Bone Joint Surg Br.2005;87:361–366. , , , .
- History of the Rochester Epidemiology Project.Mayo Clin Proc.1996;71:266–274. .
- The mortality and social prognosis of hip fractures. A prospective multifactorial study.Int Orthop.1994;18(2):109–113. .
- Functional outcome after hip fracture. A 1‐year prospective outcome study of 275 patients.Injury.2003;34:529–532. , .
- Rate of mortality for elderly patients after fracture of the hip in the 1980's.J Bone Joint Surg Am.1987;69:1335–1340. , , .
- Hip fractures in the elderly. Mortality, functional results and social readaptation.Int Surg.1989;74(3):191–194. , , , .
- Blood transfusion requirements in femoral neck fracture.Injury.2000;31(1):7–10. , , .
- Mortality and causes of death after hip fractures in The Netherlands.Neth J Med.1992;41(1–2):4–10. , , .
- Influence of preoperative medical status and delay to surgery on death following a hip fracture.ANZ J Surg.2002;72:405–407. , , .
- Predictors of mortality and institutionalization after hip fracture: the New Haven EPESE cohort. Established Populations for Epidemiologic Studies of the Elderly.Am J Public Health.1994;84:1807–1812. , , ,
- Mortality risk after hip fracture.J Orthop Trauma.2003;17(1):53–56. , , , .
- Thirty‐day mortality following hip arthroplasty for acute fracture.J Bone Joint Surg Am.2004;86‐A:1983–1988. , , .
- Functional outcomes and mortality vary among different types of hip fractures: a function of patient characteristics.Clin Orthop Relat Res.2004:64–71. , , , , .
- Implementation of a voluntary hospitalist service at a community teaching hospital: improved clinical efficiency and patient outcomes.Ann Intern Med.2002;137:859–865. , , , , , .
- Effects of physician experience on costs and outcomes on an academic general medicine service: results of a trial of hospitalists.Ann Intern Med.2002;137:866–874. , , , et al.
- The future of hip fractures in the United States. Numbers, costs, and potential effects of postmenopausal estrogen.Clin Orthop Relat Res1990 (252):163–166. , , .
- Hip fractures in the elderly: a world‐wide projection.Osteoporos Int.1992;2:285–289. , , .
- The economic cost of hip fractures among elderly women. A one‐year, prospective, observational cohort study with matched‐pair analysis.Belgian Hip Fracture Study Group.J Bone Joint Surg Am.2001;83‐A:493–500. , , , .
- Estimating hip fracture morbidity, mortality and costs.J Am Geriatr Soc.2003;51:364–370. , , .
- The aging of America. Impact on health care costs.JAMA.1990;263:2335–2340. , .
- Medical expenditures for the treatment of osteoporotic fractures in the United States in 1995: report from the National Osteoporosis Foundation.J Bone Miner Res.1997;12(1):24–35. , , , .
- US Department of Health and Human Services.Surveillance for selected public health indicators affecting older adults —United States.MMWR Morb Mortal Wkly Rep1999;48:33–34.
- Epidemiology and outcomes of osteoporotic fractures.Lancet.2002;359:1761–1767. , .
- Effects of a hospitalist model on elderly patients with hip fracture.Arch Intern Med.2005;165:796–801. , , , et al.
- Hip fractures in Finland and Great Britain—a comparison of patient characteristics and outcomes.Int Orthop.2001;25:349–354. , , .
- WHO.International Classification of Disease, Ninth Revision (ICD‐9).Geneva, Switzerland:World Health Organization;1977.
- Medical and surgical comanagement after elective hip and knee arthroplasty: a randomized, controlled trial.Ann Intern Med.2004;141(1):28–38. , , , et al.
- Regression models and life‐tables (with discussion).J R Stat Soc Ser B.1972;34:187–220. .
- Nonparametric estimation from incomplete observations.J Am Statistical Assoc.1958;53:457–481. , .
- An Introduction to Recursive Partitioning using the RPART Routines: Section of Biostatistics, Mayo Clinic;1997. , .
- Computer Intensive Statistical Methods, Validation, Model Selection, and Bootstrap.London:Chapman and Hall;1994. .
- A bootstrap resampling procedure for model building: application to the Cox regression model.Stat Med.1992;11:2093–2109. , .
- Associations between the hospitalist model of care and quality‐of‐care‐related outcomes in patients undergoing hip fracture surgery.Mayo Clin Proc.2006;81(1):28–31. , , .
- Association of timing of surgery for hip fracture and patient outcomes.JAMA.2004;291:1738–1743. , , , et al.
- The effects of time‐to‐surgery on mortality and morbidity in patients following hip fracture.Am J Med.2002;112:702–709. , , , , .
- Morbidity and mortality after hip fracture: the impact of operative delay.Arch Orthop Trauma Surg.2004;124:334–340. , , , .
- Delay to surgery prolongs hospital stay in patients with fractures of the proximal femur.J Bone Joint Surg Br.2005;87:1123–1126. , , .
- The timing of surgery for proximal femoral fractures.J Bone Joint Surg Br.1992;74(2):203–205. , .
- Hospital readmissions after hospital discharge for hip fracture: surgical and nonsurgical causes and effect on outcomes.J Am Geriatr Soc.2003;51:399–403. , , , et al.
- Mortality after hip fractures.Acta Orthop Scand1979;50(2):161–167. , .
- Medical complications and outcomes after hip fracture repair.Arch Intern Med.2002;162:2053–2057. , , , , .
- Development and initial validation of a risk score for predicting in‐hospital and 1‐year mortality in patients with hip fractures.J Bone Miner Res.2005;20:494–500. , , , et al.
- Outcome after hip fracture in individuals ninety years of age and older.J Orthop Trauma.2001;15(1):34–39. , , , , .
- Hip fractures in the elderly: predictors of one year mortality.J Orthop Trauma.1997;11(3):162–165. , , , .
- The effect of hospital type and surgical delay on mortality after surgery for hip fracture.J Bone Joint Surg Br.2005;87:361–366. , , , .
- History of the Rochester Epidemiology Project.Mayo Clin Proc.1996;71:266–274. .
- The mortality and social prognosis of hip fractures. A prospective multifactorial study.Int Orthop.1994;18(2):109–113. .
- Functional outcome after hip fracture. A 1‐year prospective outcome study of 275 patients.Injury.2003;34:529–532. , .
- Rate of mortality for elderly patients after fracture of the hip in the 1980's.J Bone Joint Surg Am.1987;69:1335–1340. , , .
- Hip fractures in the elderly. Mortality, functional results and social readaptation.Int Surg.1989;74(3):191–194. , , , .
- Blood transfusion requirements in femoral neck fracture.Injury.2000;31(1):7–10. , , .
- Mortality and causes of death after hip fractures in The Netherlands.Neth J Med.1992;41(1–2):4–10. , , .
- Influence of preoperative medical status and delay to surgery on death following a hip fracture.ANZ J Surg.2002;72:405–407. , , .
- Predictors of mortality and institutionalization after hip fracture: the New Haven EPESE cohort. Established Populations for Epidemiologic Studies of the Elderly.Am J Public Health.1994;84:1807–1812. , , ,
- Mortality risk after hip fracture.J Orthop Trauma.2003;17(1):53–56. , , , .
- Thirty‐day mortality following hip arthroplasty for acute fracture.J Bone Joint Surg Am.2004;86‐A:1983–1988. , , .
- Functional outcomes and mortality vary among different types of hip fractures: a function of patient characteristics.Clin Orthop Relat Res.2004:64–71. , , , , .
- Implementation of a voluntary hospitalist service at a community teaching hospital: improved clinical efficiency and patient outcomes.Ann Intern Med.2002;137:859–865. , , , , , .
- Effects of physician experience on costs and outcomes on an academic general medicine service: results of a trial of hospitalists.Ann Intern Med.2002;137:866–874. , , , et al.
Copyright © 2007 Society of Hospital Medicine