The Assessment of SpondyloArthritis international Society (ASAS) developed criteria for the diagnosis of axial spondylarthritis. Two sets of criteria are reported in an extended report.
Patient selection: chronic back pain (>= 3 months) with age at onset < 45 years
Set 1 Criteria for the diagnosis of axial spondyloarthritis - one or both of the following:
(1) sacroiliitis on imaging studies AND >= 1 spondyloarthritis features
(2) presence of >=3 spondyloarthritis features
Set 2 Criteria for the diagnosis of axial spondyloarthritis - one or both of the following:
(1) sacroiliitis on imaging studies AND >= 1 spondyloarthritis features
(2) inflammatory back pain and presence of >=2 spondyloarthritis features
Sacroiliitis on imaging studies - one or both of the following:
(1) active inflammation identified on MRI highly suggestive of sacroiliitis
(2) definite radiographic sacroiliitis using the modified New York criteria
Spondyloarthritis features:
(1) inflammatory back pain
(2) extra-spinal manifestations (see below)
(3) good response to NSAIDs
(4) family history of spondyloarthritis
(5) HLA-B27
(6) elevated CRP (or ESR
Extra-spinal manifestations
(1) arthritis
(2) enthesitis involving the heel
(3) uveitis
(4) dactylitis
(5) psoriasis
(6) idiopathic inflammatory bowel disease (ulcerative colitis or Crohn's disease)
In Set 1, one or more extra-spinal manifestations counts as 1 feature.
In Set 2, one extra-spinal manifestation count as 1 feature while two or more counts as 2.
Performance:
• The first set has sensitivity of 97% and specificity of 95%.
• The second set has sensitivity of 86% and specificity of 95%.
