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


CONCLUSIONS
Our results of meta-analysis do not support the hypothesis of a protective effect of oral contraceptives on the risk for RA in women.
Department of Anesthesiology, China-Japan Union Hospital. Jilin University, Changchun, Jilin, People’s Republic of China.
Shuang
S
Qi
Department of Radiology, 2nd Hospital affiliated to Jilin University, Jilin, People's Republic of China.
Rui
R
Xin
Intensive Care Unit, 2nd Hospital affiliated to Jilin University, Jilin, People's Republic of China.
Weina
W
Guo
Department of Hand Surgery, China-Japan Union Hospital, Jilin University, Changchun, Jilin, People's Republic of China.
Yan
Y
Liu
hormone; meta-analysis; oral contraceptive; rheumatoid arthritis