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Table 163-1

ASAS Criteria for Classification of Axial Spondyloarthritis (To Be Applied for Pts with Back Pain ≥3 Months and Age of Onset <45 Years)a

SACROILIITIS ON IMAGING PLUS ≥1 SPA FEATUREORHLA-B27 PLUS ≥2 OTHER SPA FEATURES

Sacroiliitis on imaging

  • Active (acute) inflammation on MRI highly suggestive of SpA-associated sacroiliitisb

    and/or

  • Definite radiographic sacroiliitis according to modified New York criteriac

SpA features

  • 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; MRI, magnetic resonance imaging; NSAIDs, nonsteroidal anti-inflammatory drugs; SpA, spondyloarthritis.

Source: Rudwaleit M et al: The development of assessment of spondyloarthritis international society classification criteria for axial spondyloarthritis (part II). Ann Rheum Dis 68:777, 2009. Adapted by permission from BMJ Publishing Group Limited.