Fair Conduct and Fair Reporting of Clinical Trials

Meta-analysis, done properly, is a systematic effort to search for and winnow out all the best evidence and show how well a given intervention works. It is crucially dependent on the identification of all available data from clinical trials. In 1989, Gøtzsche,¹ who was performing a meta-analysis of 244 trials of nonsteroidal anti-inflammatory drugs in rheumatoid arthritis, drew attention to a practice that seemed to subvert the normal process of publication as well as of meta-analysis. Excluding abstracts, letters, and brief versions, Gøtzsche found 44 multiple publications of 31 of the clinical trials, 20 trials published twice, 10 three times, and 1 trial 5 times, with the overall proportion of multiple publications being at least 18%. The fact that the data had been published elsewhere was not noted in 32 of the 44 articles. Indeed, in about half of them, the first author and number of authors were different, and in half there were important discrepancies between the various versions of the same trial. Gøtzsche¹ pointed out that "some cases were so difficult to detect that in a meta-analysis they might have been mistaken for separate trials."