Discrepancies among megatrials

The validity of meta-analyses has recently been examined by comparing their results with those of megatrials on the same topic. We investigated the reliability of this gold standard by identifying megatrials, defined as ones involving more than 1000 subjects, in the recent issue of the Cochrane Library and in the article by LeLorier et al. (N Engl J Med 1997;337:536-42). In the former set, 289 pairs of megatrials were identified which studied …