Table 1.

Characteristics included in ASAS, Amor, and ESSG criteria.

ASAS (axial): Sacroiliitis on imaging plus ≥ 1 SpA feature, or HLA-B27 plus ≥ 2 SpA features:
  Inflammatory back pain*
  Enthesitis (heel)
  Good response to NSAID
  Family history for SpA
  Elevated CRP
ASAS (peripheral): Arthritis or enthesitis or dactylitis plus either ≥ 1 SpA feature, or ≥ 2 SpA features
  ≥ 1 SpA features:  ≥ 2 SpA features:
    Uveitis    Arthritis
    Psoriasis    Enthesitis
    IBD    Dactylitis
    Preceding infection    IBP ever
    HLA-B27    Family history for SpA
    Sacroiliitis on imaging
Amor: Clinical symptoms or history of
  Lumbar or dorsal pain during the night, or morning stiffness of lumbar or dorsal spine
  Asymmetric oligoarthritis
  Buttock pain, if affecting alternately the right or the left buttock
  Heel pain or any other well defined enthesopathy (enthesitis)
  Nongonoccal urethritis or cervicitis accompanying, or within 1 month before, the onset of arthritis
  Presence or history of psoriasis, banalitis, or IBD
  Radiological findings
  Genetic background
    HLA-B27 or family history of SpA
  Response to treatment
    Good response to NSAID in < 48 h
Inflammatory spinal pain or synovitis (asymmetric or predominantly in the lower limbs), and ≥ 1 SpA feature:
  Positive family history
  Urethritis, cervicitis, or acute diarrhea within 1 month before arthritis
  Alternating buttock pain
  • Patient age at onset < 45 yrs and ≥ 3 months’ back pain (for axial predominant disease).

  • * Four out of 5 of the following measures present: (1) age at onset < 40 yrs, (2) insidious onset, (3) improvement with exercise, (4) no improvement with rest, and (5) pain at night (with improvement upon getting up). ASAS: Assessment in Spondyloarthritis International Society; ESSG: European Spondylarthropathy Study Group; SpA: spondyloarthritis; NSAID: nonsteroidal antiinflammatory drugs; CRP: C-reactive protein; IBD: inflammatory bowel disease; IBP: inflammatory back pain.