The oral contraceptive pill (OCP) has been implicated as having a protective effect on the development of rheumatoid arthritis (RA). The results of 12 studies have now been reported and produced differing results and conclusions. Because of the discrepancy in results and the importance of the issue we undertook a review of the studies and performed a meta-analysis. In all, 9 independent studies satisfied the criteria for selection, 6 case-control design and 3 longitudinal. Using standard meta-analysis techniques, the overall pooled odds ratio for all the studies was 0.68 for the crude results (95
作者：T D, Spector；M C, Hochberg
来源：Journal of clinical epidemiology 1990 年 43卷 11期
