common framework for variable definition, we also requested original data from all studies that appeared to meet inclusion criteria published prior to 2008.10,15-28 We received original data in a usable format for the meta-analysis from 10 of the 14 study investigators. A total of 14 studies were included in the analysis, 15-20,23,25-27,29-32 10 of which15-20,23,25-27,29,30 were also included in a second sex-specific meta-analysis of original data. Nine other studies did not meet inclusion criteria.33-41
