Baseline characteristics
| First anti-TNF drug: | |||||||
|---|---|---|---|---|---|---|---|
| Characteristics | DMARD (n=3232)* | All anti-TNF (n=10 712)* | p Value† | ETA (n=3913) | INF (n=3295) | ADA (n=3504) | p Value‡ |
| Age (years), mean (SD) | 60 (12) | 56 (12) | <0.001 | 56 (12) | 56 (12) | 57 (12) | 0.012 |
| Women (%) | 72 | 76 | <0.001 | 77 | 76 | 75 | 0.108 |
| 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, mean (SD) | 1.5 (0.8) | 2.0 (0.6) | <0.001 | 2.1 (0.6) | 2.1 (0.5) | 2.0 (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 |
| Number of prior DMARDs, median (IQR) | 2 (1–3) | 4 (3–5) | <0.001 | 4 (3–5) | 4 (3–5) | 3 (3–5) | <0.001 |
| Baseline steroid use, n (%) | 744 (23) | 4753 (44) | <0.001 | 1860 (48) | 1520 (46) | 1373 (39) | <0.001 |
| Diabetes, n (%) | 212 (6.6) | 596 (5.6) | 0.034 | 236 (6.1) | 156 (4.8) | 204 (5.9) | 0.042 |
| COPD/asthma, n (%) | 590 (18.4) | 1429 (13.5) | <0.001 | 558 (14.4) | 423 (13.0) | 448 (12.9) | 0.104 |
| Prior TB, n (%) | 74 (2.3) | 201 (1.8) | 0.193 | 96 (2.5) | 53 (1.5) | 52 (1.5) | 0.05 |
| Smoking, n (%) | |||||||
| Current | 751 (23) | 2334 (22) | 0.013 | 805 (21) | 718 (22) | 811 (23) | 0.057 |
| Former | 1273 (40) | 4067 (38) | 1485 (38) | 1247 (38) | 1335 (38) | ||
| Never | 1191 (37) | 4249 (40) | 1599 (41) | 1314 (40) | 1336 (38) | ||
| Ethnicity, n (%) | |||||||
| White | 2509 (78) | 8873 (83) | <0.001 | 3228 (82) | 2704 (82) | 2941 (84) | 0.363 |
| Non-white | 59 (2) | 366 (3) | 124 (3) | 124 (4) | 118 (3) | ||
| Missing | 664 (21) | 1473 (14) | 561 (14) | 467 (14) | 445 (13) | ||
| Entry year, n (%) | |||||||
| Before | 2003 11 (0) | 1322 (12) | <0.001 | 181 (5) | 1112 (34) | 29 (1) | <0.001 |
| 2003 | 306 (9) | 2924 (27) | 1440 (37) | 1063 (32) | 421 (12) | ||
| 2004 | 886 (27) | 3092 (29) | 1876 (48) | 485 (15) | 731 (21) | ||
| 2005 | 925 (29) | 1537 (14) | 412 (11) | 326 (10) | 799 (23) | ||
| 2006+ | 1104 (34) | 1837 (17) | 4 (0) | 309 (10) | 1524 (43) | ||
↵* Two hundred and five patients switched from the DMARD cohort to the anti-TNF cohort and contributed person-years to both cohorts;
↵† p value represents the significance of differences between the DMARD and anti-TNF cohorts using x2 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 x2 tests for categorical outcomes and Kruskal–Wallis rank tests for continuous variables.
ADA, adalimumab; COPD, chronic obstructive pulmonary disease; DAS28, 28 joint count Disease Activity Score; DMARDs, disease-modifying antirheumatic drugs; ETA, etanercept;
HAQ, Health Assessment Questionnaire; INF, infliximab; TB, tuberculosis; TNF, tumour necrosis factor.