Transparency and reporting characteristics of COVID-19 randomized controlled trials

Randomized controlled trials (RCTs) are essential to support clinical decision making. We assessed the transparency, completeness and consistency of reporting of 244 reports (120 peer-reviewed journal publications; 124 preprints) of RCTs assessing pharmacological interventions for the treatment of COVID-19 published the first 17 months of the pandemic (up to May 31, 2021). Transparency was poor. Only 55% of trials were prospectively registered; 39% made their full protocols available and 29% provided access to their statistical analysis plan. Only 6% completely reported the most important information. Primary outcome(s) reported in trial registries and published reports were inconsistent in 47% of trials. Of the 124 RCTs published as preprint, 76 were secondarily published in a peer-reviewed journal. There was no major improvement after the peer-review process. Lack of transparency, completeness and consistency of reporting is an important barrier to trust, interpretation and synthesis in COVID-19 clinical trials.