Table 2.

ASAS classification criteria for axial and peripheral SpA, after Rudwaleit, et al8,9,10.

Axial SpA Criteria8,9Peripheral SpA Criteria10
In patients with ≥ 3 months back pain and age at onset < 45 yrsIn patients with peripheral symptoms ONLY
Sacroiliitis on imaging plus ≥ 1 SpA feature ORHLA-B27 plus ≥ 2 other SpA featuresArthritis or enthesitis or dactylitis plus
SpA features:≥ 1 SpA feature:
· Inflammatory back pain (IBP)· Uveitis
· Arthritis· Psoriasis
· Enthesitis (heel)· Crohn disease/colitis
· Uveitis· Preceding infection
· Dactylitis· HLA-B27
· Psoriasis· Sacroiliitis on imaging
· Crohn disease/colitisOR
· Good response to NSAID≥ 2 other SpA features:
· Family history for SpA· Arthritis
· HLA-B27· Enthesitis
· Elevated CRP· Dactylitis
· IBP ever
· Family history for SpA
  • The Axial SpA criteria have sensitivity of 79.5% and specificity of 83.3% (n = 975). ASAS: Assessment of Spondyloarthritis Society; CRP: C-reactive protein; NSAID: nonsteroidal antiinflammatory drugs; SpA: spondyloarthritis; IBP: inflammatory back pain.