Design: The MEDLINE and the Cochrane Library databases were searched for studies conducted from 1966 through 2005. Relative risks were pooled by using an inverse-variance weighted random effects model.

• 设计：搜索MEDLINE和冠心病图书馆数据库中从1966年到2005年的研究，采用一种反变量加权的随机效应模型计算相对危险度。