ASAS Criteria for Classification of Axial Spondyloarthritis (to be Applied for Patients with Back Pain≥3 MONTHS AND AGE OF ONSET <2001 and Harmonizing Definition Criteria for the Metabolic Syndromea
| Sacroiliitis on Imaging Plus or ≥1 SpA Feature | HLA-B27 Plus ≥ 2 Other SpA Features |
|---|---|
| Sacroiliitis on imaging | SpA features |
• Active (acute) inflammation on MRI highly suggestive of SpA-associated sacroiliitisb and/or • Definite radiographic sacroiliitis according to modified New York criteriac | • Inflammatory back paind • Arthritise • Enthesitis (heel)f • Anterior uveitisg • Dactylitise • Psoriasise • Crohn's disease or ulcerative colitise • Good response to NSAIDsh • Family history of SpAi • HLA-B27 • Elevated CRPj |
aSensitivity 83%, specificity 84%. The imaging arm (sacroiliitis) alone has a sensitivity of 66% and a specificity of 97%.
bBone marrow edema and/or osteitis on short tau inversion recovery (STIR) or gadolinium-enhanced T1 image.
cBilateral grade ≥2 or unilateral grade 3 or 4.
dSee text for criteria.
ePast or present, diagnosed by a physician.
fPast or present pain or tenderness on examination at calcaneus insertion of Achilles tendon or plantar fascia.
gPast or present, confirmed by an ophthalmologist.
hSubstantial relief of back pain at 24-48 h after a full dose of NSAID.
iFirst- or second-degree relatives with ankylosing spondylitis (AS), psoriasis, uveitis, reactive arthritis (ReA), or inflammatory bowel disease (IBD).
jAfter exclusion of other causes of elevated CRP.
Abbreviations: ASAS, Assessment of Spondyloarthritis International Society; CRP, C-reactive protein; SpA, spondyloarthritis.
Source: From M Rudwaleit et al: Ann Rheum Dis 68:777, 2009. Copyright 2009, with permission from BMJ Publishing Group Ltd.