Meta-analysis of oral contraceptives and rheumatoid arthritis risk in women

Background and objectives: Epidemiological investigations of the relationship between oral contraceptives and rheumatoid arthritis (RA) risk have reported controversial results. Therefore, a meta-analysis of case-control or cohort studies was performed to evaluate the role of oral contraceptives in relation to risk of developing RA. Methods: Eligible studies were identified from databases PubMed and EMBASE by searching and reviewing references. Random effect models were utilized to summarize the relative risk (RR) estimates with 95% confidence intervals (CIs). Results: A total of 12 case-control studies and five cohort studies were eligible for our analysis. No statistically significant association was observed between oral contraceptives and RA risk (RR=0.88, 95% CI=0.75-1.03). In the subgroup of geographic area, a decreased risk of borderline significance was observed for oral contraceptive users in European studies (RR=0.79, 95% CI=0.62-1.01), but this association did not emerge in the North American studies group (RR=0.99, 95% CI=0.81-1.21). No evidence for publication bias was detected (P for Egger's test =0.231). Conclusion: Our results of meta-analysis do not support the hypothesis of a protective effect of oral contraceptives on the risk for RA in women.