AxSpA (n=294) mean (SD) or n (%) | Non-axSpA (n=123) mean (SD) or n (%) | |
Males | 152 (52)† | 30 (24)† |
Age at inclusion, in years | 30 (8) | 31 (8) |
Body mass index | 24 (5) | 24 (5) |
Duration of back pain, in months | 13 (7) | 13 (7) |
Spondyloarthritis features | ||
Inflammatory back pain | 209 (71) | 78 (63) |
Peripheral arthritis | 66 (22)† | 11 (8.9)† |
Dactylitis | 30 (10)† | 1 (0.8)† |
Heel enthesitis | 93 (32)† | 15 (12)† |
Uveitis | 36 (12)† | 6 (4.9)† |
Inflammatory bowel disease | 18 (6.1) | 8 (6.5) |
Psoriasis | 43 (15) | 11 (8.9) |
Family history‡ | 139 (47)† | 72 (59)† |
Good response of back pain to NSAIDs | 134 (46)† | 41 (33)† |
HLA-B27 positivity | 214 (73)† | 32 (26)† |
Elevated C-reactive protein (≥5 mg/L) | 102 (35)† | 28 (23)† |
Positive MRI-SIJ (ASAS definition)§ | 116 (39)† | 4 (3.3)† |
Positive X-SIJ (mNY criteria) § | 15 (5.1)† | 0† |
ASAS classification criteria§ | 212 (72) | n/a |
Treatment | ||
NSAIDs at baseline | 217 (74) | 81 (66) |
NSAIDs at 2 years | 190 (65)† | 48 (39)† |
NSAIDs (“ever use” during the 2 year follow-up) | 276 (94)† | 97 (79)† |
csDMARDs at baseline | 19 (6.5)† | 2 (1.6)† |
csDMARDs at 2 years | 25 (8.5) | 4 (3.3) |
bDMARDs at baseline | 8 (2.7) | 1 (0.8) |
Anti-TNF | 8 | 1¶ |
Other bDMARDs | 0 | 0 |
bDMARDs at 2 years | 57 (19)† | 2 (1.6)† |
Anti-TNF | 53 | 2¶ |
Other bDMARDs | 4 | 0 |
*Comparisons between groups using Chi-square test for dichotomous variables and unpaired t-test for continuous variables.
†p-value <0.05.
‡ASAS definition: presence in first or second-degree relatives of spondyloarthritis, psoriasis, uveitis, reactive arthritis or inflammatory bowel disease.
§According to central reading.
¶1 patient with inflammatory bowel disease; 1 patient with inflammatory bowel disease and psoriasis.
Anti-TNF, tumour necrosis factor inhibitor; ASAS, Assessment of Spondyloarthritis International Society; axSpA, axial spondyloarthritis; bDMARDs, biologic disease modifying antirheumatic drugs; csDMARDs, conventional synthetic disease modifying antirheumatic drugs; mNY, modified New York criteria; MRI-SIJ, magnetic resonance imaging of the sacroiliac joints; n/a, not applicable; NSAIDs, nonsteroidal anti-inflammatory drugs; X-SIJ, definite damage on radiographs of the sacroiliac joints.