Baseline characteristics
| Values are mean (SD) or n (%). | |
| DAS28, 28 joint disease activity score; HAQ, health assessment questionnaire score; SF-36, 36 item short form health survey score. | |
| Number of cases | 7818 |
| Age (years) | 56 (12) |
| Female | 6012 (77%) |
| Current smokers | 1676 (21%) |
| Ever smoked | 4602 (59%) |
| Disease duration (years) | 14 (9) |
| Steroids | 3793 (49%) |
| DAS28 | 6.6 (1.0) |
| HAQ | 2.1 (0.6) |
| SF-36 mental component scale | 42 (8) |
| SF-36 physical component scale | 26 (6) |