New Peripheral SpA Criteria Improved on Existing Schemes

COPENHAGEN — New criteria for diagnosing peripheral spondylarthritis from the Assessment of Spondyloarthritis International Society had a higher sensitivity and specificity than did either of the diagnostic schemes currently used.

The new criteria “performed well in patients with predominantly peripheral manifestations [of spondyloarthritis (SpA)], and appeared to be better balanced in [this] study” than were the two diagnostic formulas most often used today: the system of the European Spondylarthropathy Study Group (ESSG), and the system developed by Dr. Bernard Amor, said Dr. Martin Rudwaleit at the annual European Congress of Rheumatology. Both the ESSG and the Amor criteria were first introduced nearly 20 years ago.

“I assume that, in the past, many patients who were thought to have undifferentiated arthritis had, in fact, SpA. These patients will be better captured with the new criteria. The new criteria were designed to help rheumatologists [who are] less experienced with SpA,” said Dr. Rudwaleit, a rheumatologist at Charité University Hospital Berlin and a member of the Assessment of Spondyloarthritis International Society (ASAS).

The new peripheral SpA criteria complement the new ASAS criteria, published in June, for diagnosing predominantly axial SpA (Ann. Rheum. Dis. 2009;68:770-6;777-83).

The major difference between the new peripheral SpA criteria and the ESSG and Amor criteria is the addition of positivity for HLA B27 as a strong determinant of SpA, along with peripheral arthritis, enthesitis, or dactylitis, Dr. Rudwaleit said in an interview. “HLA B27 is an important marker for SpA.”

Many rheumatologists who specialize in SpA “would say that if a patient has peripheral arthritis and has HLA B27, and if you rule out other possibilities such as peripheral rheumatoid arthritis, then they have SpA, and this is really new for the criteria. It's probably why the sensitivity was better. The ESSG misses these patients because in them HLA B27 has no role. In the Amor criteria, peripheral arthritis and HLA B27 without additional SpA features do not suffice for classifying a patient with SpA.”

Among the patients who were used to test the criteria, HLA B27 occurred in 46% of those diagnosed with SpA by the experts, compared with 6% of patients who were not diagnosed with SpA.

To develop the new peripheral SpA diagnostic criteria, the ASAS invited its membership of about 100 rheumatologists to participate; 28 members were actively involved. They developed two slightly different sets of criteria that they then tested using a multicenter series of 266 patients with predominantly peripheral arthritis of the SpA type.

Each participating ASAS rheumatologist carefully examined each peripheral arthritis patient at his or her institution, and determined a “gold standard” diagnosis of either SpA or not-SpA, based on experience and judgment. They diagnosed 176 patients (66%) with SpA; the remaining 90 patients didn't have SpA, the experts said. Each patient was then assessed by both of the new, draft ASAS criteria sets, as well as by the ESSG and Amor criteria.

The ASAS criteria set that performed best is useful in diagnosing peripheral SpA in patients who present with peripheral arthritis of the SpA type (asymmetric, lower limb, or both), enthesitis, or dactylitis, plus at least one additional feature from list 1, or at least two additional features from list 2. (See box.)

When applied to the 266 test patients and compared with the diagnosis of each patient by the consulting ASAS experts, the ASAS criteria had a sensitivity of 75% and specificity of 82%. In contrast, the ESSG criteria had a sensitivity of 55% and a specificity of 81%, the Amor criteria had a sensitivity of 35% and a specificity of 98%, and the alternative ASAS criteria had a sensitivity of 63% and a specificity of 90%, Dr. Rudwaleit reported.

The new ASAS criteria will be published toward the end of the year.

Dr. Rudwaleit said that he and his associates had no relevant conflicts of interest to disclose.

ASAS Criteria for Peripheral SpA

Patients need to have peripheral arthritis (asymmetric, lower limb, or both), enthesitis, or dactylitis, plus either:

At least one of these features:

Crohn's disease

HLA B27

Preceding infection

Psoriasis

Sacroiliitis on MRI/x-ray imaging

Uveitis

Or at least two of these features:

Arthritis

Dactylitis

Enthesitis

Family history of spondyloarthritis

Inflammatory back pain

Source: Dr. Rudwaleit

COPENHAGEN — New criteria for diagnosing peripheral spondylarthritis from the Assessment of Spondyloarthritis International Society had a higher sensitivity and specificity than did either of the diagnostic schemes currently used.

The new criteria “performed well in patients with predominantly peripheral manifestations [of spondyloarthritis (SpA)], and appeared to be better balanced in [this] study” than were the two diagnostic formulas most often used today: the system of the European Spondylarthropathy Study Group (ESSG), and the system developed by Dr. Bernard Amor, said Dr. Martin Rudwaleit at the annual European Congress of Rheumatology. Both the ESSG and the Amor criteria were first introduced nearly 20 years ago.

“I assume that, in the past, many patients who were thought to have undifferentiated arthritis had, in fact, SpA. These patients will be better captured with the new criteria. The new criteria were designed to help rheumatologists [who are] less experienced with SpA,” said Dr. Rudwaleit, a rheumatologist at Charité University Hospital Berlin and a member of the Assessment of Spondyloarthritis International Society (ASAS).

The new peripheral SpA criteria complement the new ASAS criteria, published in June, for diagnosing predominantly axial SpA (Ann. Rheum. Dis. 2009;68:770-6;777-83).

The major difference between the new peripheral SpA criteria and the ESSG and Amor criteria is the addition of positivity for HLA B27 as a strong determinant of SpA, along with peripheral arthritis, enthesitis, or dactylitis, Dr. Rudwaleit said in an interview. “HLA B27 is an important marker for SpA.”

Many rheumatologists who specialize in SpA “would say that if a patient has peripheral arthritis and has HLA B27, and if you rule out other possibilities such as peripheral rheumatoid arthritis, then they have SpA, and this is really new for the criteria. It's probably why the sensitivity was better. The ESSG misses these patients because in them HLA B27 has no role. In the Amor criteria, peripheral arthritis and HLA B27 without additional SpA features do not suffice for classifying a patient with SpA.”

Among the patients who were used to test the criteria, HLA B27 occurred in 46% of those diagnosed with SpA by the experts, compared with 6% of patients who were not diagnosed with SpA.

To develop the new peripheral SpA diagnostic criteria, the ASAS invited its membership of about 100 rheumatologists to participate; 28 members were actively involved. They developed two slightly different sets of criteria that they then tested using a multicenter series of 266 patients with predominantly peripheral arthritis of the SpA type.

Each participating ASAS rheumatologist carefully examined each peripheral arthritis patient at his or her institution, and determined a “gold standard” diagnosis of either SpA or not-SpA, based on experience and judgment. They diagnosed 176 patients (66%) with SpA; the remaining 90 patients didn't have SpA, the experts said. Each patient was then assessed by both of the new, draft ASAS criteria sets, as well as by the ESSG and Amor criteria.

The ASAS criteria set that performed best is useful in diagnosing peripheral SpA in patients who present with peripheral arthritis of the SpA type (asymmetric, lower limb, or both), enthesitis, or dactylitis, plus at least one additional feature from list 1, or at least two additional features from list 2. (See box.)

When applied to the 266 test patients and compared with the diagnosis of each patient by the consulting ASAS experts, the ASAS criteria had a sensitivity of 75% and specificity of 82%. In contrast, the ESSG criteria had a sensitivity of 55% and a specificity of 81%, the Amor criteria had a sensitivity of 35% and a specificity of 98%, and the alternative ASAS criteria had a sensitivity of 63% and a specificity of 90%, Dr. Rudwaleit reported.

The new ASAS criteria will be published toward the end of the year.

Dr. Rudwaleit said that he and his associates had no relevant conflicts of interest to disclose.

ASAS Criteria for Peripheral SpA

Patients need to have peripheral arthritis (asymmetric, lower limb, or both), enthesitis, or dactylitis, plus either:

At least one of these features:

Crohn's disease

HLA B27

Preceding infection

Psoriasis

Sacroiliitis on MRI/x-ray imaging

Uveitis

Or at least two of these features:

Arthritis

Dactylitis

Enthesitis

Family history of spondyloarthritis

Inflammatory back pain

Source: Dr. Rudwaleit

COPENHAGEN — New criteria for diagnosing peripheral spondylarthritis from the Assessment of Spondyloarthritis International Society had a higher sensitivity and specificity than did either of the diagnostic schemes currently used.

The new criteria “performed well in patients with predominantly peripheral manifestations [of spondyloarthritis (SpA)], and appeared to be better balanced in [this] study” than were the two diagnostic formulas most often used today: the system of the European Spondylarthropathy Study Group (ESSG), and the system developed by Dr. Bernard Amor, said Dr. Martin Rudwaleit at the annual European Congress of Rheumatology. Both the ESSG and the Amor criteria were first introduced nearly 20 years ago.

“I assume that, in the past, many patients who were thought to have undifferentiated arthritis had, in fact, SpA. These patients will be better captured with the new criteria. The new criteria were designed to help rheumatologists [who are] less experienced with SpA,” said Dr. Rudwaleit, a rheumatologist at Charité University Hospital Berlin and a member of the Assessment of Spondyloarthritis International Society (ASAS).

The new peripheral SpA criteria complement the new ASAS criteria, published in June, for diagnosing predominantly axial SpA (Ann. Rheum. Dis. 2009;68:770-6;777-83).

The major difference between the new peripheral SpA criteria and the ESSG and Amor criteria is the addition of positivity for HLA B27 as a strong determinant of SpA, along with peripheral arthritis, enthesitis, or dactylitis, Dr. Rudwaleit said in an interview. “HLA B27 is an important marker for SpA.”

Many rheumatologists who specialize in SpA “would say that if a patient has peripheral arthritis and has HLA B27, and if you rule out other possibilities such as peripheral rheumatoid arthritis, then they have SpA, and this is really new for the criteria. It's probably why the sensitivity was better. The ESSG misses these patients because in them HLA B27 has no role. In the Amor criteria, peripheral arthritis and HLA B27 without additional SpA features do not suffice for classifying a patient with SpA.”

Among the patients who were used to test the criteria, HLA B27 occurred in 46% of those diagnosed with SpA by the experts, compared with 6% of patients who were not diagnosed with SpA.

To develop the new peripheral SpA diagnostic criteria, the ASAS invited its membership of about 100 rheumatologists to participate; 28 members were actively involved. They developed two slightly different sets of criteria that they then tested using a multicenter series of 266 patients with predominantly peripheral arthritis of the SpA type.

Each participating ASAS rheumatologist carefully examined each peripheral arthritis patient at his or her institution, and determined a “gold standard” diagnosis of either SpA or not-SpA, based on experience and judgment. They diagnosed 176 patients (66%) with SpA; the remaining 90 patients didn't have SpA, the experts said. Each patient was then assessed by both of the new, draft ASAS criteria sets, as well as by the ESSG and Amor criteria.

The ASAS criteria set that performed best is useful in diagnosing peripheral SpA in patients who present with peripheral arthritis of the SpA type (asymmetric, lower limb, or both), enthesitis, or dactylitis, plus at least one additional feature from list 1, or at least two additional features from list 2. (See box.)

When applied to the 266 test patients and compared with the diagnosis of each patient by the consulting ASAS experts, the ASAS criteria had a sensitivity of 75% and specificity of 82%. In contrast, the ESSG criteria had a sensitivity of 55% and a specificity of 81%, the Amor criteria had a sensitivity of 35% and a specificity of 98%, and the alternative ASAS criteria had a sensitivity of 63% and a specificity of 90%, Dr. Rudwaleit reported.

The new ASAS criteria will be published toward the end of the year.

Dr. Rudwaleit said that he and his associates had no relevant conflicts of interest to disclose.

ASAS Criteria for Peripheral SpA

Patients need to have peripheral arthritis (asymmetric, lower limb, or both), enthesitis, or dactylitis, plus either:

At least one of these features:

Crohn's disease

HLA B27

Preceding infection

Psoriasis

Sacroiliitis on MRI/x-ray imaging

Uveitis

Or at least two of these features:

Arthritis

Dactylitis

Enthesitis

Family history of spondyloarthritis

Inflammatory back pain

Source: Dr. Rudwaleit