NON-CONTRACEPTIVE HORMONES AND THE RISK OF RHEUMATOID-ARTHRITIS IN MENOPAUSAL WOMEN

Background. Several reproductive factors appear to affect a woman's risk of developing rheumatoid arthritis. This study's purpose was to determine whether use of non-contraceptive hormones is among them. Methods. A population-based case-control study was conducted in King County, Washington and Group Health Cooperative of Puget Sound, a prepaid health plan. New cases of rheumatoid arthritis in peri- or postmenopausal women (n = 135) were verified through clinical examination and compared with 592 controls. Both groups were interviewed in person about hormone use and demographic and reproductive factors. Results. The age-adjusted relative risk (RR) among women who had ever used non-contraceptive oestrogens was 1.04 (95% confidence interval [CI] : 0.70-1.55), and among women who had ever used progestins it was 0.66 (95% CI 0.40-1.08). For current users of oestrogen only, the RR was 0.97 (95% CI : 0.62-1.53), and among current users of oestrogen plus progestin it was 0.81 (95% CI : 0.45-1.45). Multivariate analyses yielded similar results. There was little evidence of a dose-response relationship with duration of use or with frequency of progestin use. Conclusions. Use of non-contraceptive oestrogens appears to have little effect on the risk of developing rheumatoid arthritis in menopausal women. There may be a modest reduction in risk among progestin users.