rheumatology

ASAS Criteria for Axial Spondyloarthritis (Axial SpA)

Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axial SpA in patients with chronic back pain ≥3 months onset age <45 years. Includes radiographic (AS) and non-radiographic axial SpA.

Sacroiliitis on imaging (MRI — active inflammation consistent with SpA OR X-ray — Grade ≥2 bilateral or Grade 3–4 unilateral sacroiliitis per modified New York criteria)*

HLA-B27 positive*

Inflammatory back pain (ASAS criteria: ≥4 of 5 — onset <40y, insidious onset, improvement with exercise, no improvement with rest, night pain with improvement on getting up)*

Peripheral arthritis (past or present inflammatory arthritis)*

Enthesitis (heel or other site — past or present)*

Uveitis (anterior — past or present confirmed by ophthalmologist)*

Dactylitis (past or present)*

Psoriasis (past or present confirmed by physician)*

Crohn's disease or ulcerative colitis (past or present confirmed)*

Family history of SpA (1st or 2nd degree relative with AS, PsA, acute uveitis, IBD, or reactive arthritis)*

Good response to NSAIDs (pain/stiffness much improved ≤48h; or worsens ≤48h after stopping)*

Elevated CRP or ESR (not explained by other cause)*

Score interpretation

Criteria Not Met 0–1

Neither imaging nor clinical arm criteria met

→ Consider alternative diagnoses; if high clinical suspicion, repeat MRI after 3–6 months; rheumatology referral for specialist assessment; NSAID trial for symptomatic relief

Apply ASAS Arms 2–13

Apply ASAS arm criteria: Imaging arm (sacroiliitis + ≥1 SpA feature) OR Clinical arm (HLA-B27 + ≥2 SpA features)

→ If imaging arm positive: axial SpA diagnosed; MRI or X-ray confirm sacroiliitis. If clinical arm positive: non-radiographic axial SpA. Management: NSAIDs, physiotherapy; if inadequate response: anti-TNF or IL-17 inhibitor (secukinumab/ixekizumab); consider referral to SpA specialist

Interpretation bands for the ASAS Axial SpA. Apply clinical judgement and local guidance.

References

Rudwaleit M et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis. Ann Rheum Dis. 2009;68(6):777–783.

Curated clinical cross-links plus same-class fallbacks.

Calculators

BASDAI — Bath Ankylosing Spondylitis Disease Activity Index · Spondyloarthritis

Drugs

Pathways

Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.

Score interpretation

References

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