Cases (n = 136) | Controls (n = 544) | |
Age at RA diagnosis* | 63.3 (8.25) | NA |
RF positive | 68.4% (91/133 tested) | NA |
ANA positive | 30.5% (25/82 tested) | NA |
Anti-CCP positive | 66.7% (16/24 tested) | NA |
Age at screening* | 57.9 (7.33) | 58.0 (7.32) |
Ever used OCs† | 63 (48.5%) | 254 (49.4%) |
Never used OCs | 67 (51.2%) | 259 (51.2%) |
Used OCs 1–5 years | 18 (14.0%) | 110 (21.7%) |
Used OCs >5 years | 44 (34.1%) | 137 (27.1%) |
Given birth to ⩾1 child | 106 (77.9%) | 445 (81.8%) |
Breast fed for 0 months | 43 (31.6%) | 137 (25.2%) |
Breast fed for 1–12 months | 74 (54.4%) | 297 (54.6%) |
Breast fed for >13 months | 19 (14.0%) | 110 (20.2%) |
*Values are mean (SD).
†Data on OC use were available for 130 cases and 514 controls.
ANA, anti-nuclear antibodies; CCP, cyclic citrullinated peptides; NA, not applicable; OC, oral contraceptive; RA, rheumatid arthritis; RF, rheumatoid factor.