Baseline demographic and disease characteristics of the study sample
| Variable | Value |
|---|---|
| N | 1251 |
| Age at registration (years): median (IQR) | 57.1 (46.6, 68.4) |
| Female: no. (%) | 820 (65.5) |
| Symptoms duration (months): median (IQR) | 5.7 (3.1, 10.1) |
| Current smoker at registration: no. (%) | 307 (26.6) |
| Satisfied 1987 ACR criteria for RA at registration: no. (%) | 611 (48.8) |
| RF positive: no. (%)* | 367 (32.9) |
| Presence of nodules: no. (%) | 93 (7.4) |
| Shared epitope (1/2 alleles): no. (%)† | 517 (47.1)/158 (14.4) |
| Swollen joint count out of 51: median (IQR) | 5 (2, 12) |
| Tender joint count out of 51: median (IQR) | 6 (2, 16) |
| Swollen joint count out of 28: median (IQR) | 4 (1, 10) |
| Tender joint count out of 28: median (IQR) | 4 (1, 11) |
| CRP (mg/l): median (IQR)‡ | 7.1 (2, 20) |
| DAS28–CRP (3): median (IQR)‡ | 3.9 (2.9, 4.9) |
| HAQ score: median (IQR) | 0.9 (0.4, 1.5) |
*RF factor measured on 1114 subjects.
†Shared epitope measured on 1097 subjects.
‡CRP measured on 1042 subjects.
ACR, American college of rheumatology; CRP, C reactive protein; DAS, Disease Activity Score; HAQ, Health Assessment Questionnaire; RA, rheumatoid arthritis; RF, rheumatoid factor.