Reporting of Adverse Events in Published and Unpublished Studies of Health Care Interventions: A Systematic Review

Background: We performed a systematic review to assess whether we can quantify the underreporting of adverse events (AEs) in the published medical literature documenting the results of clinical trials as compared with other nonpublished sources, and whether we can measure the impact this underreporting has on systematic reviews of adverse events. Methods and Findings: Studies were identified from 15 databases (including MEDLINE and Embase) and by handsearching, reference checking, internet searches, and contacting experts. The last database searches were conducted in July 2016. There were 28 methodological evaluations that met the inclusion criteria. Of these, 9 studies compared the proportion of trials reporting adverse events by publication status. Conclusions: There is strong evidence that much of the information on adverse events remains unpublished and that the number and range of adverse events is higher in unpublished than in published versions of the same study. The inclusion of unpublished data can also reduce the imprecision of pooled effect estimates during meta-analysis of adverse events. In a systematic review, Su Golder and colleagues study the completeness of adverse event reporting, mainly associated with pharmaceutical interventions, in published articles as compared with other information sources.Why Was This Study Done?: What Did the Researchers Do and Find?: What Do These Findings Mean?: