Table 1.
Baseline characteristics of the cohorts
| sDMARD | All TNFi | First TNFi drug | |||
|---|---|---|---|---|---|
| N=3249 | N=11 767 | ETA | INF | ADA | |
| N=4073 | N=3457 | N=4237 | |||
| Mean age: years (SD) | 60 (12) | 56 (12) | 56 (12) | 56 (12) | 56 (12) |
| Female: % | 2381 (73) | 8977 (76) | 3150 (77) | 2614 (76) | 3213 (76) |
| Smoking history (%) | |||||
| Current smoker | 770 (24) | 2569 (22) | 834 (22) | 756 (22) | 979 (23) |
| Former smoker | 1276 (39) | 4466 (38) | 1551 (38) | 1309 (38) | 1606 (38) |
| Never smoked | 1188 (37) | 4656 (40) | 1661 (41) | 1374 (40) | 1621 (38) |
| Not recorded | 14 (0) | 76 (1) | 27 (1) | 18 (1) | 31 (1) |
| Ethnicity (%) | |||||
| White | 2459 (76) | 9725 (83) | 3380 (83) | 2798 (81) | 3547 (84) |
| Other | 62 (2) | 407 (3) | 141 (3) | 126 (4) | 140 (3) |
| Not recorded | 728 (22) | 1635 (14) | 552 (14) | 533 (15) | 550 (13) |
| Mean DAS28 (SD) | 5.3 (1.1) | 6.6 (1.0) | 6.6 (0.9) | 6.6 (1.0) | 6.5 (1.0) |
| Mean HAQ (SD) | 1.5 (0.7) | 2.0 (0.6) | 2.1 (0.6) | 2.1 (0.5) | 1.9 (0.6) |
| Median disease duration: years (IQR) | 6 (1, 15) | 11 (6, 19) | 12 (6, 19) | 12 (6, 19) | 10 (5, 18) |
| Baseline steroid use: (%) | 726 (22) | 5190 (44) | 1949 (48) | 1596 (46) | 1645 (39) |
| Number of prior sDMARDs: median (IQR) | 2 (1, 3) | 4 (3, 5) | 4 (3, 5) | 4 (3, 5) | 3 (3, 4) |
| Co-morbidity* (%) | |||||
| None | 1358 (42) | 5466 (46) | 1840 (45) | 1626 (47) | 2000 (47) |
| 1 co-morbidity | 1123 (35) | 4043 (34) | 1388 (34) | 1212 (35) | 1443 (34) |
| 2 co-morbidities | 535 (16) | 1662 (14) | 616 (15) | 470 (14) | 576 (14) |
| ≥3 co-morbidities | 233 (7) | 596 (5) | 229 (6) | 149 (4) | 218 (5) |
| Year of registration (%) | |||||
| Pre-2003 | 7 (0) | 1410 (12) | 203 (5) | 1177 (34) | 30 (1) |
| 2003 | 279 (9) | 2070 (26) | 1498 (37) | 1102 (32) | 470 (11) |
| 2004 | 752 (23) | 3227 (27) | 1951 (48) | 495 (14) | 781 (18) |
| 2005 | 797 (25) | 1613 (14) | 418 (10) | 346 (10) | 849 (20) |
| 2006 | 668 (21) | 1125 (10) | 2 (0) | 272 (8) | 851 (20) |
| 2007 | 331 (10) | 843 (7) | 1 (0) | 65 (2) | 777 (18) |
| 2008–2009 | 415 (13) | 479 (4) | 0 (0) | 0 (0) | 479 (11) |
*Hypertension, ischaemic heart disease (myocardial infarction or angina), stroke, asthma, bronchitis or emphysema, diabetes mellitus, depression, renal disease and liver disease.
ADA, adalimumab; DAS28, disease activity score; ETA, etanercept; HAQ, Health Assessment Questionnaire; INF, infliximab; sDMARD, synthetic disease modifying antirheumatic drug; TNFi, tumour necrosis factor inhibitor.