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。