A Cross-Sectional Study on the Usefulness of Posted Results Data from Trial Registries for Meta-Analyses on Cognitive Behavioral Therapy

Introduction: Posting results to clinical trial registers is encouraged and even mandatory for certain trials. This study assessed the feasibility of using structured results data from ClinicalTrials.gov for meta-analyses on Cognitive Behavioral Therapy (CBT) using two exemplary approaches. Methods: In study one, we searched ClinicalTrials.gov for studies employing CBT for Major Depressive Disorder (MDD) and extracted posted results. We evaluated whether the data were sufficient for running a meta-analysis. In study two, we selected a published meta-analysis on digital interventions for depression, extracted all registrations of the primary sources, and assessed if the meta-analysis could be reproduced using posted results.Results: For study one, we identified 179 completed studies on CBT for MDD from ClinicalTrials.gov. 16 of 179 studies had posted results and 15 had reported depression outcomes, using various psychological scales, such as the BDI-II. This low number of posted results and the heterogeneity of reported scales made running a meta-analysis infeasible. In study two, using 83 primary sources of a published meta-analysis, we obtained 59 registrations. Only three studies had posted results, all to ClinicalTrials.gov. Again, this made running or reproducing the meta-analysis infeasible.Conclusion: The potential for clinical trial registries to support meta-analyses is substantial, yet few studies on psychotherapy post their results. Core results of clinical trials should be openly available in a timely manner and in a structured format. Currently, it seems that the posting of results data is so uncommon that running meta-analyses using structured results data from trial registries is practically impossible.