“…In 14 studies [13], [29]–[32], [35], [37]–[39], [44], [47], [49], [53], the WHO criteria were used, and, in four studies, CHD was diagnosed based on a clinical diagnosis [6], [33], [45]. Controls arose from the source population of the cases in 21 studies [6], [8], [13], [29], [31]–[33], [35]–[38], [45], [47], [49]–[53], [55], while hospital-based/not population-based controls were used in 17 studies [7], [10], [11], [30], [34], [39]–[44], [46], [48], [54], [56]–[58].…”