Demographic, disease characteristics and treatments of patients with axSpA stratified by gender
| Total axSpA n=2719 | Male n=1858 (68.3) | Female n=861 (31.7) | P value | Standardised difference | |
| Age at study visit | 41.9 (13.1) | 41.4 (13.2) | 42.9 (12.6) | <0.01 | −0.116 |
| Smoking habit (ever) | 1185 (43.6) | 910 (49.0) | 275 (31.9) | <0.001 | 0.354 |
| Alcohol (ever) | 1089 (40.1) | 886 (47.7) | 203 (23.6) | <0.001 | 0.52 |
| Body mass index (kg/m2) | 25.9 (5.1) | 25.8 (4.7) | 26.0 (5.8) | 0.56 | −0.038 |
| University education | 1178 (43.4) | 830 (44.7) | 348 (40.4) | 0.04 | 0.087 |
| Family history of SpA | 964 (35.5) | 628 (33.8) | 336 (39.0) | <0.01 | −0.108 |
| Diagnosis delay (years) since the first symptom | 5.8 (7.7) | 5.6 (7.6) | 6.2 (7.9) | 0.08 | −0.077 |
| Symptom duration | 14.4 (11.1) | 14.8 (11.4) | 13.4 (10.4) | <0.01 | 0.128 |
| Axial involvement according to the rheumatologist | 2651 (97.5) | 1816 (97.7) | 835 (97.0) | 0.24 | 0.044 |
| Inflammatory back pain (ASAS criteria) | 2544 (93.6) | 1733 (93.3) | 811 (94.2) | 0.35 | −0.037 |
| Sacroiliitis on imaging. n/N (%) by: | |||||
| xRay mNY criteria | 2042/2645 (75.4) | 1507/1812 (83.2) | 535/833 (64.2) | <0.001 | 0.442 |
| MRI-SIJ, ASAS def | 1469/1783 (82.3) | 950/1146 (82.9) | 519/637 (81.5) | 0.45 | 0.037 |
| mNY criteria or ASAS def | 2499/2694 (92.8) | 1746/1841 (94.8) | 753/853 (88.3) | <0.001 | 0.235 |
| HLA-B27 positive | 1709/2178 (78.8) | 1238/1490 (83.1) | 471/677 (69.6) | <0.001 | 0.322 |
| Elevated CRP (>5 mg/L) | 1902 (70.0) | 1352 (75.4) | 550 (65.6) | <0.001 | 0.216 |
| CRP (mg/L) | 11.7 (26.6) | 12.5 (27.6) | 9.8 (24.2) | 0.01 | 0.104 |
| Peripheral arthritis | 978 (36.0) | 637 (34.3) | 341 (39.6) | <0.01 | −0.11 |
| Enthesitis | 1113 (40.9) | 725 (39.0) | 388 (45.1) | <0.01 | −0.124 |
| Dactylitis | 164 (6.0) | 105 (5.7) | 59 (6.9) | 0.22 | −0.049 |
| Psoriasis | 187 (6.9) | 109 (5.9) | 78 (9.1) | <0.01 | −0.122 |
| IBD | 132 (4.9) | 81 (4.4) | 51 (5.9) | 0.08 | −0.068 |
| Uveitis | 588 (21.6) | 406 (21.9) | 182 (21.1) | 0.67 | 0.019 |
| Concomitant fibromyalgia according to: | |||||
| Treating rheumatologist | 212 (7.8) | 62 (3.3) | 150 (17.4) | <0.001 | −0.476 |
| FiRST questionnaire | 427 (17.2) | 219 (13.1) | 208 (25.8) | <0.001 | −0.325 |
| csDMARD (ever) | 1402 (51.6) | 930 (50.1) | 472 (54.8) | <0.05 | −0.094 |
| bDMARD (ever) | 1613 (59.3) | 1121 (60.3) | 492 (57.1) | 0.12 | 0.065 |
Results are shown as absolute numbers (percentages) or mean (SD). Estimates with p<0.05 are highlighted in bold. Standardised difference scores of 0.2, 0.5 and 0.8 represent small, medium and large effect sizes, respectively.
ASAS, Assessment of SpondyloArthritis International Society; axSpA, axial spondyloarthritis; bDMARD, biological disease-modifying antirheumatic drug; CRP, C reactive protein; csDMARD, conventional synthetic disease-modifying antirheumatic drug; FiRST, Fibromyalgia Rapid Screening Tool; IBD, inflammatory bowel disease.