Baseline characteristics of study population
| Characteristic | nbDMARD n=3673 | All TNF n=11881 | p Value* | Etanercept n=4139 | Infliximab n=3475 | Adalimumab n=4267 | p Value† |
|---|---|---|---|---|---|---|---|
| Age, years, mean (SD) | 60 (12) | 56 (12) | <0.001 | 56 (12) | 56 (12) | 57 (12) | 0.018 |
| Gender, (% female) | 2652 (72) | 9053 (76) | <0.001 | 3193 (77) | 2626 (76) | 3234 (76) | 0.203 |
| DAS28,‡ mean (SD) | 5.1 (1.3) | 6.6 (1.0) | <0.001 | 6.6 (1.0) | 6.6 (1.0) | 6.5 (1.0) | <0.001 |
| HAQ score,§ mean (SD) | 1.5 (0.8) | 2.0 (0.6) | <0.001 | 2.1 (0.6) | 2.1 (0.5) | 1.9 (0.6) | <0.001 |
| Disease duration, years, median (IQR) | 6 (1, 15) | 11(6, 19) | <0.001 | 12 (6, 19) | 12 (6, 19) | 10 (5, 18) | <0.001 |
| Baseline steroid use, n (%) | 845 (23) | 5228 (44) | <0.001 | 1979 (48) | 1609 (46) | 1664 (39) | <0.001 |
| Diabetes, n (%) | 234 (6.7) | 675 (5.8) | 0.033 | 255 (6) | 169 (4) | 261 (6) | 0.026 |
| COPD, n (%) | 304 (8) | 570 (5) | <0.001 | 222 (5) | 165 (5) | 183 (4) | 0.070 |
| Smoking, n (%) | |||||||
| Current | 868 (24) | 2580 (22) | 0.001 | 846 (21) | 757 (22) | 977 (23) | 0.029 |
| Ex | 1454 (40) | 4510 (38) | 1576 (38) | 1314 (38) | 1620 (38) | ||
| Never | 1333 (36) | 4714 (40) | 1691 (41) | 1386 (40) | 1637 (39) | ||
↵* p Value represents the significance of differences between the nbDMARD and anti-TNF cohorts using χ2 tests for categorical outcomes and Wilcoxon rank sum tests for continuous variables.
↵† p Value represents the significance of differences between the three anti-TNF drugs using χ2 tests for categorical outcomes and Kruskal–Wallis rank tests for continuous variables.
↵‡ DAS28 range 0–10; >5.1 high disease activity, 3.2–5.1 moderate activity, 2.1–3.2 low disease activity, <2.1 remission.
↵§ HAQ scale 0–3, 3 indicating worst disability.
COPD, chronic obstructive pulmonary disease; DAS28, 28-joint disease activity score; nbDMARD, non-biological disease-modifying antirheumatic drug; HAQ, health assessment questionnaire; TNF, tumour necrosis factor.