Baseline demographics and disease characteristics
| AS | uSpA | |||||||
|---|---|---|---|---|---|---|---|---|
| All N=1365 | csDMARD comedication N=557 | No csDMARD comedication N=808 | p Value | All N=1155 | csDMARD comedication N=581 | No csDMARD comedication N=574 | p Value | |
| Age, mean (SD) | 43.8 (12.3) | 43.6 (12.2) | 43.9 (12.4) | 0.692 | 42.6 (12.1) | 42.8 (12.4) | 42.3 (11.9) | 0.520 |
| Sex, n (%) male | 995 (72.9) | 410 (73.6) | 585 (72.4) | 0.622 | 606 (52.5) | 293 (50.4) | 313 (54.5) | 0.163 |
| TNFi type | <0.001 | <0.001 | ||||||
| Adalimumab, n (%) | 406 (29.7) | 114 (20.5) | 292 (36.1) | 326 (28.2) | 123 (21.2) | 203 (35.4) | ||
| Etanercept, n (%) | 354 (25.9) | 108 (19.4) | 246 (30.4) | 391 (33.9) | 192 (33.0) | 199 (34.7) | ||
| Infliximab, n (%) | 605 (44.3) | 335 (60.1) | 270 (33.4) | 438 (37.9) | 266 (45.8) | 172 (30.0) | ||
| Year of TNFi start | <0.001 | <0.001 | ||||||
| 2003–2006, n (%) | 459 (33.6) | 254 (45.6) | 205 (25.4) | 460 (39.8) | 274 (47.2) | 186 (32.4) | ||
| 2007–2010, n (%) | 906 (66.4) | 303 (54.4) | 603 (74.6) | 695 (60.2) | 307 (52.8) | 388 (67.6) | ||
| csDMARD comedication | NA | NA | ||||||
| MTX, n (%) | 389 (28.5) | 401 (34.7) | ||||||
| SSZ, n (%) | 108 (7.9) | 100 (8.7) | ||||||
| Other, n (%)* | 60 (4.4) | 80 (6.9) | ||||||
| None, n (%) | 808 (59.2) | 574 (49.7) | ||||||
| MTX dose, mg, mean (SD)†‡ | 13.9 (4.9) (N=424)‡ | 15.8 (5.3) (N=456)‡ | ||||||
| Disease duration (years), median (25, 75 percentile)† | 14.0 (6.7, 24.7) (N=1327) | 13.4 (6.7, 24.1) (N=537) | 14.6 (6.4, 25.0) (N=790) | 0.514 | 8.7 (3.2, 17.5) (N=1135) | 7.9 (3.0, 16.3) (N=571) | 9.5 (3.5, 18.9) (N=564) | 0.079 |
| Number of previous csDMARDs, mean (SD)/median (25th, 75th percentile) | 0.40 (0.69) 0 (0, 1) | 0.54 (0.78) 0 (0, 1) | 0.30 (0.60) 0 (0, 0) | <0.001 | 0.43 (0.84) 0 (0, 1) | 0.49 (0.86) 0 (0, 1) | 0.38 (0.82) 0 (0, 0) | 0.001 |
| ESR (mm/h), median (25th, 75th percentile)† | 20 (10, 37) (N=1104) | 24 (10.25, 40.75) (N=496) | 18 (9, 34) (N=608) | 0.001 | 18 (8, 36) (N=989) | 20 (10, 41) (N=540) | 16 (8, 33.5) (N=449) | 0.003 |
| CRP (mg/L), median (25th, 75th percentile)† | 13 (5, 30) (N=1055) | 17 (7, 36) (N=485) | 12 (5, 25) (N=570) | <0.001 | 11 (4, 27.5) (N=929) | 12 (5, 35) (N=519) | 9 (3, 21) (N=410) | <0.001 |
| Patient global VAS, mean (SD)† | 57.5 (24.0) (N=925) | 57.3 (23.7) (N=433) | 59.0 (24.3) (N=492) | 0.784 | 61.0 (21.7) (N=924) | 60.8 (21.9) (N=507) | 61.3 (21.5) (N=417) | 0.731 |
| 28-swollen joint count ≥1, n (%)† | 260 (28.8) (N=904) | 159 (37.3) (N=426) | 101 (21.1) (N=478) | <0.001 | 421 (46.1) (N=913) | 270 (53.0) (N=509) | 151 (37.4) (N=404) | <0.001 |
| 28-swollen joint count, mean (SD)/median (25th, 75th percentile)† | 1.1 (2.6) 0 (0, 1) (N=904) | 1.4 (2.9) 0 (0, 2) (N=426) | 0.8 (2.2) 0 (0, 0) (N=478) | <0.001 | 1.8 (3.1) 0 (0, 2) (N=913) | 2.2 (3.4) 1 (0, 3) (N=509) | 1.3 (2.6) 0 (0, 2) (N=404) | <0.001 |
| Uveitis, n (%) | 361 (26.4) | 153 (27.5) | 208 (25.7) | 0.477 | 205 (17.7) | 93 (16.0) | 112 (19.5) | 0.119 |
| Inflammatory bowel disease, n (%) | 120 (8.8) | 57 (10.2) | 63 (7.8) | 0.118 | 120 (10.4) | 54 (9.3) | 66 (11.5) | 0.220 |
| Psoriasis, n (%) | 67 (4.9) | 29 (5.2) | 38 (4.7) | 0.672 | 116 (10.0) | 61 (10.5) | 55 (9.6) | 0.604 |
| Number of hospital days, mean (SD)/median (25th, 75th percentile)§ | 3.6 (12.2) 0 (0, 1) | 3.4 (10.6) 0 (0, 1) | 3.8 (13.2) 0 (0, 1) | 0.663 | 5.0 (17.4) 0 (0, 3) | 5.7 (21.8) 0 (0, 2.5) | 4.3 (11.1) 0 (0, 3) | 0.641 |
| Number of outpatient visits, mean (SD) / median (25th, 75th percentile)§ | 7.6 (6.7) 6 (3, 10) | 8.0 (6.4) 6 (3, 11) | 7.3 (6.9) 5 (3, 10) | 0.008 | 10.6 (9.2) 8 (5, 14) | 11.3 (9.4) 9 (5, 15) | 9.8 (9.0) 7 (4, 13) | 0.001 |
| Disposable income (in 1000 €), mean (SD)¶ | 22.0 (16.0) (N=1342) | 21.0 (13.8) (N=552) | 22.7 (17.3) (N=790) | 0.066 | 22.0 (21.5) (N=1149) | 21.0 (14.3) (N=577) | 23.0 (26.8) (N=572) | 0.102 |
| Education | 0.256 | 0.079 | ||||||
| 9 years or less, n (%) | 229 (16.8) | 101 (18.1) | 128 (15.8) | 172 (14.9) | 100 (17.2) | 72 (12.5) | ||
| 10–12 years, n (%) | 686 (50.3) | 270 (48.5) | 416 (51.5) | 553 (47.9) | 281 (48.4) | 272 (47.4) | ||
| >12 years, n (%) | 424 (31.1) | 179 (32.1) | 245 (30.3) | 423 (36.6) | 197 (33.9) | 226 (39.4) | ||
| Missing data, n (%) | 26 (1.9) | 7 (1.3) | 19 (2.4) | 7 (0.6) | 3 (0.5) | 4 (0.7) | ||
*Including combinations of several csDMARDs (for AS 40 of these included MTX, for other SpA 59 of these included MTX).
†Data on these variables were incomplete; numbers of patients with available data are given in square brackets.
‡Including patients using combination of MTX and other csDMARDs as comedication.
§During the period 2 years prior to TNFi start.
¶2008 data used for patients started on TNFi in 2010, data from the year prior for all other patients.
AS, ankylosing spondylitis; CRP, C-reactive protein; csDMARD, conventional synthetic disease modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; MTX, methotrexate; SSZ, sulfasalazine; TNFi, tumour necrosis factor inhibitor; uSpA, undifferentiated spondyloarthritis; VAS, visual analogue scale.