Patient and disease characteristics according to employment status
| Features | All (n=3114) | Employed (n=1943) | Not employed (n=1155) | P values* |
| Age (years), mean (SD) | 40.9 (11.8) | 40.1 (10.5) | 42.2 (13.6) | <0.001 |
| Disease duration (years), mean (SD) | 7.6 (8.5) | 7.3 (8.0) | 8.2 (9.3) | 0.005 |
| Gender (male), n (%) | 2047 (65.7) | 1387 (71.4) | 652 (56.6) | <0.001 |
| Education, n (%) | ||||
| University | 1366 (44.0) | 961 (49.6) | 398 (34.5) | <0.001 |
| Secondary | 1375 (44.2) | 842 (43.4) | 526 (45.6) | |
| Lower | 367 (11.8) | 136 (7.0) | 229 (19.9) | |
| RDCI (0 to 8), mean (SD) | 0.7 (1.0) | 0.5 (0.9) | 0.9 (1.2) | <0.001 |
| ASDAS-CRP, mean (SD) | 2.0 (1.1) | 1.9 (1.0) | 2.3 (1.1) | <0.001 |
| BASFI (0–10), mean (SD) | 3.0 (2.7) (n=3095) | 2.5 (2.4) (n=1941) | 4.0 (2.9) (1153) | <0.001 |
| ASAS classification criteria | ||||
| Axial SpA, n (%) | 2764 (88.8) | 1727 (88.9) | 1023 (88.6) | 0.790 |
| Peripheral SpA, n (%) | 350 (11.2) | 216 (11.1) | 132 (11.4) | |
| Axial SpA | ||||
| Imaging arm (±clinical arm), n (%) | 2546 (92.1) | 1582 (91.6) | 952 (93.1) | 0.170 |
| Clinical arm only, n (%) | 218 (7.9) (n = 2754) | 145 (8.4) (n = 1727) | 71 (6.9) (n = 1023) | |
| Radiographic sacroiliitis (mNY), n (%) | 2225 (75.2) | 1357 (73.7) | 859 (78.0) | 0.009 |
| Sacroiliitis on MRI (ASAS), n (%) | 1204 (71.3) (n=1688) | 780 (72.4) (n=1204) | 419 (70.0) (n=484) | 0.296 |
| HLA-B27 positivity, n (%) | 1967 (76.7) (n=2566) | 1266 (77.1) (n=1967) | 692 (76.0) (n=599) | 0.563 |
| Elevated CRP (ever), n (%) | 1767 (60.0) | 1078 (58.4) | 680 (62.7) | 0.020 |
| Current medication, n (%) | ||||
| Oral steroids | 335 (10.9) | 183 (9.5) | 152 (13.2) | 0.001 |
| NSAIDs | 2130 (68.9) | 1311 (67.6) | 819 (71.0) | 0.045 |
| csDMARDs | 1059 (34.2) | 651 (33.5) | 408 (35.3) | 0.302 |
| bDMARDs | 1175 (37.7) | 708 (36.4) | 456 (39.5) | 0.091 |
Missing <5%: employment status; disease duration; education; marital status; RDCI; BASFI; radiographic sacroiliitis; absenteeism; oral steroids; NSAIDs. Missing 5%–10%: ASDAS-CRP; CRP status. The total number of patients includes 16 patients with missing data regarding their employment status.
*Comparison between employed and unemployed (independent-samples t-test for continuous variables and χ2 for categorical variables).
ASAS, Assessment of SpondyloArthritis international Society; ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score—C Reactive Protein; BASFI, Bath Ankylosing Spondylitis Functional Index; bDMARDs, biological disease-modifying antirheumatic drugs; csDMARDs, synthetic disease-modifying antirheumatic drugs; HLA-B27, human leucocyte antigen B27; mNY, modified New York criteria; NSAIDs, non-steroidal anti-inflammatory drugs; RDCI, Rheumatic Disease Comorbidity Index; SpA, spondyloarthritis.