Douglas Altman's 2009 Grand Lecture: Can we trust our literature?

Recent studies of the medical literature have revealed numerous and serious problems. Errors in the design, methods and interpretation of studies can frequently be identified. A huge hidden problem is publication bias, the tendency for positive articles to be published, while negative articles are either not written or submitted. This can systematically lead to an overestimation of the value of treatments, of diagnostic or prognostic studies. Even more worrisome is selective reporting: only a subset of a wide array of tested hypotheses are presented (the ones that turned out to be positive with significance testing). This is particularly true for secondary endpoints and subgroup findings, but even the primary endpoints of trials have been modified when publications are compared to protocols. The peer-review process is fallible. Even if it were strengthened, reviewers cannot examine what is not reported. Hence many problems can only be mitigated with better reporting. Numerous initiatives have proposed guidelines to promote transparent reporting, but progress is slow.