Oral contraceptives and rheumatoid arthritis: further evidence for a preventive effect

Abstract

To investigate a reported negative association between the use of oral contraceptives (OC) and the development of rheumatoid arthritis, a case-control study was undertaken to compare the histories of OC use between 228 women with a diagnosis of probable or definite rheumatoid arthritis and 302 women with the diagnosis of soft-tissue rheumatism and/or osteoarthritis. The use of OCs before the onset of joint complaints was acknowledged by 31.1% of the rheumatoid arthritis patients and by 55.6% of the controls. After adjustment for possible confounding variables, the rate ratio for ever use became 0.42 (95% confidence interval 0.27--0.65), while it was 0.40 (0.22-0.72) for ex-users and 0.45 (0.28-0.75) for current users. These findings confirm the finding from the Royal College of General Practitioners Oral Contraceptive Study that the incidence rate of rheumatoid arthritis among OC users was halved.

PIP: In order to study a reported negative association between the use of oral contraceptives (OCs) and the development of rheumatoid arthritis, a case-control study was undertaken to compare the histories of OC use between 228 women with a diagnosis of probable or definite rheumatoid arthritis and 302 women with the diagnosis of soft-tissue rheumatism and/or osteoarthritis. 31.1% of the rheumatoid arthritis patients and 55.6% of the controls used OCs before the onset of joint complaints. The adjusted rate ratio for ever use is 0.42 while it was 0.40 for ex-users and 0.45 for current users. The results confirm the theory that OC use is associated with a halving of the incidence rate for rheumatoid arthritis in both current and ex-users. It was also found that OC use effects seropositive more than seronegative rheumatoid arthritis. These results call for further elaboration of biological models of hormonal influences on autoimmune phenomena.