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.

Back pain for 3 months or more that began before age 45 (required)*

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 at the heel (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: first- or second-degree relative with ankylosing spondylitis, psoriasis, acute uveitis, reactive arthritis or IBD*

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

Elevated CRP (with back pain, other causes excluded)*

Score interpretation

Not Applicable — Entry Criterion Not Met -1

The ASAS axial SpA criteria apply only to back pain lasting 3 months or more that began before age 45.

→ Consider other causes of back pain; peripheral SpA criteria may apply if peripheral features dominate.

ASAS Axial SpA Criteria Not Met 0

Neither the imaging arm nor the clinical arm is fulfilled.

→ Consider alternative diagnoses; if suspicion remains high, rheumatology referral and MRI of the sacroiliac joints.

Axial SpA — Clinical Arm Met 1

HLA-B27 plus at least 2 other SpA features (no qualifying sacroiliitis on imaging).

→ Rheumatology review; NSAIDs and physiotherapy first line; biologic (TNF or IL-17 inhibitor) if inadequate response (ASAS-EULAR).

Axial SpA — Imaging Arm Met 2

Sacroiliitis on MRI or X-ray plus at least 1 SpA feature (radiographic axial SpA if modified New York X-ray criteria are met; non-radiographic if MRI only).

→ Rheumatology review; NSAIDs and physiotherapy first line; biologic (TNF or IL-17 inhibitor) if inadequate response (ASAS-EULAR).

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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