The Impact of Drug Trials With Financial Conflict of Interests on the Meta-analyses: A Meta-epidemiological Study

Background: To assess the impact of trials with potential financial conflict of interests (FCOIs) on evidence synthesis in meta-analyses (MAs). Methods: A total of 96 MAs from the Cochrane Library about drug trials were investigated. The primary outcomes examined the proportion of conclusions that would change with the exclusion of trials with potential FCOIs. If the proportion of changed conclusions was below the non-inferiority margin of 10%, we considered that it was not inferior to include the trials with potential FCOIs in the MAs. Results: Only 54.17% of MAs reported the funding sources of each included trial, and in 21.88% of MAs, the author-industry-related financial ties of each included trial were reported. When trials with FCOIs were excluded, the changed conclusions of effectiveness and major adverse events were 13.16% and 11.11%, respectively, and the I(2) decreased by 13.56% and 10.09%, respectively. For serious adverse events, the exclusion of FCOIs trials did not lead to any change in conclusions; however, the I(2) decreased by 24.24%. The impact of trials without reported FCOIs was also examined on evidence synthesis, and the results showed that the changed conclusions of effectiveness and major adverse events were 5.26% and 6.25%, respectively, indicating non-inferiority. However, the I(2) increased by 13.60% and 12.37%, respectively. Conclusion: In this meta-epidemiological study, we demonstrated that trials with FCOIs may not only influence the final outcome of MAs but may also increase the heterogeneity of results. It is suggested that all MAs fully report the FCOIs involved in evidence-based research and explore the impact of its FCOIs to better provide a more valuable reference for patients, clinicians, and policy-makers.