In the real world, persistence on warfarin is low

DALLAS – Less than half of patients with a first venous thromboembolism in real-world clinical practice started on warfarin within 10 days after the event, according to a large U.S. study.

Among those who did start, three-quarters discontinued use of the anticoagulant within 1 year.

"Effective and convenient anticoagulants with significant reduction in bleeding risk are needed for long-term treatment of venous thromboembolism and prevention of VTE recurrence," Dr. Xianchen Liu said at the American Heart Association scientific sessions.

Dr. Liu, director of global health economics and outcomes research at Pfizer, presented an analysis of 153,809 adults with a first deep venous thrombosis and/or pulmonary embolus was recorded in the Truven Health MarketScan Commercial and Medicare Supplemental databases. Within 10 days of diagnosis, 46% were treated with warfarin.

Dr. Liu focused on the 39,719 patients with at least 1 year of follow-up, of whom 73% had DVT as their index VTE, 24% had a pulmonary embolism, and 3% had both.

Nearly one in four patients who started on warfarin within 10 days after their index VTE discontinued the anticoagulant after 3 months, 47% after 6 months, and 75% within 1 year. The average treatment duration was 5 months, according to Dr. Liu.

Factors linked to reduced likelihood of warfarin discontinuation included comorbid atrial fibrillation, which was associated with a 25% reduction in risk of discontinuation; thrombophilia, with a 34% relative risk reduction; and pulmonary embolism, with a 24% reduction in discontinuation compared to patients with DVT only.

On the other hand, history of fracture, pregnancy, hormone therapy, or major bleeding within 6 months prior to the index VTE was associated with 24%, 35%, 13%, and 9% increased risks for warfarin discontinuation, respectively.

The clinical importance of these observations lies in the fact that roughly 900,000 incident cases of VTE occur annually in the United States. It is the most common preventable cause of death in hospitalized patients. Indeed, 2%-10% of all hospital deaths are attributed to pulmonary embolism. The VTE recurrence rate is 7%-14% within 1 year, Dr. Liu said.

Pfizer is codeveloper of the novel oral anticoagulant apixaban. Dr. Liu’s MarketScan study is based on data from 2006-2011, before novel anticoagulants became available.

Stroke prevention’s ‘major problem’

In a separate presentation, Dr. Geoffrey D. Barnes called poor warfarin persistence for stroke prevention in patients with atrial fibrillation "a major problem," citing the 38% probability of discontinuation within 1 year in his study of patients started on the drug for this indication at seven anticoagulation clinics participating in the Michigan Anticoagulation Quality Improvement Initiative.

A silver lining: One-year persistence with warfarin therapy was significantly associated with increasing CHADS2 scores. The 1-year persistence rate among the 1,901 subjects was 29% in those with a CHADS2 score of 0, 56% with a CHADS2 of 1, and 71% in those with a high CHADS2 of 2-6.

In contrast, bleeding risk as determined by baseline HAS-BLED score was unrelated to warfarin persistence, said Dr. Barnes, a cardiologist at the University of Michigan, Ann Arbor.

He reported that 85% of the Michigan patients with atrial fibrillation who discontinued warfarin did so for a known reason. That reason was a bleeding event in 8.3% of cases, change in bleeding risk in 4.7%, death in 9.5%, and ‘indication resolved’ in two-thirds of discontinuations. The likelihood of warfarin discontinuation was particularly high in patients who underwent cardioversion or catheter ablation, even though the implications of those procedures in terms of stroke risk are unresolved.

The ongoing Michigan Anticoagulation Quality Improvement Initiative is funded by Blue Cross Blue Shield of Michigan. Dr. Barnes reported having no financial conflicts of interest.

bjancin@frontlinemedcom.com

DALLAS – Less than half of patients with a first venous thromboembolism in real-world clinical practice started on warfarin within 10 days after the event, according to a large U.S. study.

Among those who did start, three-quarters discontinued use of the anticoagulant within 1 year.

"Effective and convenient anticoagulants with significant reduction in bleeding risk are needed for long-term treatment of venous thromboembolism and prevention of VTE recurrence," Dr. Xianchen Liu said at the American Heart Association scientific sessions.

Dr. Liu, director of global health economics and outcomes research at Pfizer, presented an analysis of 153,809 adults with a first deep venous thrombosis and/or pulmonary embolus was recorded in the Truven Health MarketScan Commercial and Medicare Supplemental databases. Within 10 days of diagnosis, 46% were treated with warfarin.

Dr. Liu focused on the 39,719 patients with at least 1 year of follow-up, of whom 73% had DVT as their index VTE, 24% had a pulmonary embolism, and 3% had both.

Nearly one in four patients who started on warfarin within 10 days after their index VTE discontinued the anticoagulant after 3 months, 47% after 6 months, and 75% within 1 year. The average treatment duration was 5 months, according to Dr. Liu.

Factors linked to reduced likelihood of warfarin discontinuation included comorbid atrial fibrillation, which was associated with a 25% reduction in risk of discontinuation; thrombophilia, with a 34% relative risk reduction; and pulmonary embolism, with a 24% reduction in discontinuation compared to patients with DVT only.

On the other hand, history of fracture, pregnancy, hormone therapy, or major bleeding within 6 months prior to the index VTE was associated with 24%, 35%, 13%, and 9% increased risks for warfarin discontinuation, respectively.

The clinical importance of these observations lies in the fact that roughly 900,000 incident cases of VTE occur annually in the United States. It is the most common preventable cause of death in hospitalized patients. Indeed, 2%-10% of all hospital deaths are attributed to pulmonary embolism. The VTE recurrence rate is 7%-14% within 1 year, Dr. Liu said.

Pfizer is codeveloper of the novel oral anticoagulant apixaban. Dr. Liu’s MarketScan study is based on data from 2006-2011, before novel anticoagulants became available.

Stroke prevention’s ‘major problem’

In a separate presentation, Dr. Geoffrey D. Barnes called poor warfarin persistence for stroke prevention in patients with atrial fibrillation "a major problem," citing the 38% probability of discontinuation within 1 year in his study of patients started on the drug for this indication at seven anticoagulation clinics participating in the Michigan Anticoagulation Quality Improvement Initiative.

A silver lining: One-year persistence with warfarin therapy was significantly associated with increasing CHADS2 scores. The 1-year persistence rate among the 1,901 subjects was 29% in those with a CHADS2 score of 0, 56% with a CHADS2 of 1, and 71% in those with a high CHADS2 of 2-6.

In contrast, bleeding risk as determined by baseline HAS-BLED score was unrelated to warfarin persistence, said Dr. Barnes, a cardiologist at the University of Michigan, Ann Arbor.

He reported that 85% of the Michigan patients with atrial fibrillation who discontinued warfarin did so for a known reason. That reason was a bleeding event in 8.3% of cases, change in bleeding risk in 4.7%, death in 9.5%, and ‘indication resolved’ in two-thirds of discontinuations. The likelihood of warfarin discontinuation was particularly high in patients who underwent cardioversion or catheter ablation, even though the implications of those procedures in terms of stroke risk are unresolved.

The ongoing Michigan Anticoagulation Quality Improvement Initiative is funded by Blue Cross Blue Shield of Michigan. Dr. Barnes reported having no financial conflicts of interest.

bjancin@frontlinemedcom.com

DALLAS – Less than half of patients with a first venous thromboembolism in real-world clinical practice started on warfarin within 10 days after the event, according to a large U.S. study.

Among those who did start, three-quarters discontinued use of the anticoagulant within 1 year.

"Effective and convenient anticoagulants with significant reduction in bleeding risk are needed for long-term treatment of venous thromboembolism and prevention of VTE recurrence," Dr. Xianchen Liu said at the American Heart Association scientific sessions.

Dr. Liu, director of global health economics and outcomes research at Pfizer, presented an analysis of 153,809 adults with a first deep venous thrombosis and/or pulmonary embolus was recorded in the Truven Health MarketScan Commercial and Medicare Supplemental databases. Within 10 days of diagnosis, 46% were treated with warfarin.

Dr. Liu focused on the 39,719 patients with at least 1 year of follow-up, of whom 73% had DVT as their index VTE, 24% had a pulmonary embolism, and 3% had both.

Nearly one in four patients who started on warfarin within 10 days after their index VTE discontinued the anticoagulant after 3 months, 47% after 6 months, and 75% within 1 year. The average treatment duration was 5 months, according to Dr. Liu.

Factors linked to reduced likelihood of warfarin discontinuation included comorbid atrial fibrillation, which was associated with a 25% reduction in risk of discontinuation; thrombophilia, with a 34% relative risk reduction; and pulmonary embolism, with a 24% reduction in discontinuation compared to patients with DVT only.

On the other hand, history of fracture, pregnancy, hormone therapy, or major bleeding within 6 months prior to the index VTE was associated with 24%, 35%, 13%, and 9% increased risks for warfarin discontinuation, respectively.

The clinical importance of these observations lies in the fact that roughly 900,000 incident cases of VTE occur annually in the United States. It is the most common preventable cause of death in hospitalized patients. Indeed, 2%-10% of all hospital deaths are attributed to pulmonary embolism. The VTE recurrence rate is 7%-14% within 1 year, Dr. Liu said.

Pfizer is codeveloper of the novel oral anticoagulant apixaban. Dr. Liu’s MarketScan study is based on data from 2006-2011, before novel anticoagulants became available.

Stroke prevention’s ‘major problem’

In a separate presentation, Dr. Geoffrey D. Barnes called poor warfarin persistence for stroke prevention in patients with atrial fibrillation "a major problem," citing the 38% probability of discontinuation within 1 year in his study of patients started on the drug for this indication at seven anticoagulation clinics participating in the Michigan Anticoagulation Quality Improvement Initiative.

A silver lining: One-year persistence with warfarin therapy was significantly associated with increasing CHADS2 scores. The 1-year persistence rate among the 1,901 subjects was 29% in those with a CHADS2 score of 0, 56% with a CHADS2 of 1, and 71% in those with a high CHADS2 of 2-6.

In contrast, bleeding risk as determined by baseline HAS-BLED score was unrelated to warfarin persistence, said Dr. Barnes, a cardiologist at the University of Michigan, Ann Arbor.

He reported that 85% of the Michigan patients with atrial fibrillation who discontinued warfarin did so for a known reason. That reason was a bleeding event in 8.3% of cases, change in bleeding risk in 4.7%, death in 9.5%, and ‘indication resolved’ in two-thirds of discontinuations. The likelihood of warfarin discontinuation was particularly high in patients who underwent cardioversion or catheter ablation, even though the implications of those procedures in terms of stroke risk are unresolved.

The ongoing Michigan Anticoagulation Quality Improvement Initiative is funded by Blue Cross Blue Shield of Michigan. Dr. Barnes reported having no financial conflicts of interest.

bjancin@frontlinemedcom.com