To study the effects of postmenopausal hormone therapy (PHT) on the incidence and severity of rheumatoid arthritis (RA).
The Women's Health Initiative randomized controlled trials evaluated the effects of unopposed estrogen (E-alone) and estrogen plus progestin (E+P) compared with placebo on a diverse set of health outcomes over 7.1 and 5.6 years, respectively. RA cases were identified using historical and medication data. The hazard of developing RA was estimated using Cox proportional hazards regression models. Disease symptom severity was estimated using the Short Form 36 (SF-36) and self-reported joint pain scores at baseline and after 1 year. Mean changes in severity were compared using linear regression models.
Of the 27,347 participants, 63 prevalent cases and 105 incident cases of RA were identified. A nonsignificant reduction in the risk of developing RA (hazard ratio 0.74; 95% confidence interval [95% CI] 0.51, 1.10) was noted with PHT use. PHT use led to improved SF-36 scores in unadjusted analyses (percent change 12.5%; 95% CI -24.45, -0.57) but not after adjustment for relevant covariates (P = 0.33). Nonsignificant improvements in joint pain scores were seen with PHT use (odds ratio [OR] 4.10; 95% CI 0.83, 20.20). PHT did not improve swelling (OR 1.27; 95% CI 0.08, 19.63) or prevent new joint pains (OR 0.72; 95% CI 0.11, 4.68) in RA participants.
There were no statistically significant differences in the risk of developing RA or the severity of RA between the PHT and placebo groups.