1984 Modified New York Criteria for AS

Clinical Criteria

  • Low back pain ≥ 3 months, improved by exercise and not relieved by rest
  • Limitation of lumbar spine in sagittal and frontal planes
  • Limitation of chest expansion (relative to normal values corrected for age and sex)

Radiological Criteria

  • Bilateral grade 2-4 sacroiliitis, or;
  • Unilateral 3-4 sacroiliitis


bilateral grade 2-4 or unilateral grade 3-4 sacroiliitis AND any clinical criteria (see X-Ray Grading of SI joints).


Van der Linden et al. Arthritis Rheum 1984; 27:361.

X-Ray Grading of SI Joints

ASAS Criteria for Axial SpA

ASAS Criteria for Peripheral SpA

Entry Criteria

These criteria are applicable to patients with peripheral arthritis compatible with SpA (usually asymmetric and/or predominant involvement of the lower limb), and/or enthesitis and/or dactylitis.

Additional SpA Features

IBP: IBP in the past according to the rheumatologist’s judgement

Arthritis: Past or present peripheral arthritis compatible with SpA (usually asymmetric and/or predominant involvement of lower limb)

Enthesitis: Past or present spontaneous pain or tenderness at examination of an enthesis

Uveitis: Past or present uveitis anterior, confirmed by an ophthalmologist

Dactylitis: Past or present dactylitis, diagnosed by a doctor

Psoriasis: Past or present psoriasis, diagnosed by a doctor

IBD: Past or present Crohn’s disease or ulcerative colitis diagnosed by a doctor
Preceding Infection: Urethritis/cervicitis or diarrhoea within 1 month before the onset of arthritis/enthesitis/dactylitis.

Family history for SpA: Presence in first-degree (mother, father, sisters, brothers, children) or second-degree (maternal and paternal grandparents, aunts, uncles, nieces and nephews) relatives of any of the following: (1) ankylosing spondylitis, (2) psoriasis, (3) acute uveitis, (4) reactive arthritis, (5) IBD

HLA-B27: Positive testing according to standard laboratory techniques

Sacroiliitis by Imaging: Bilateral grade 2–4 or unilateral grade 3–4 sacroiliitis on plain radiographs, according to the modified New York criteria, or active sacroiliitis on MRI according to the ASAS consensus definition