Completion and reporting of COVID-19 clinical trials registered on ClinicalTrials.gov during the first 6 months of the pandemic: cohort study

Abstract

Background: Early in the COVID-19 pandemic, numerous clinical trials were initiated. Although concerns were raised regarding the quality of the trials, the eventual research output yielded from the trials remains unknown. The objective of this study was to include all clinical trials registered on ClinicalTrials.gov during the first 6 months of the pandemic and assess if and where their results had been reported, their completion and discontinuation rates, achieved enrolment and changes made to the primary outcome after trial registration.

Methods: We included all interventional studies related to COVID-19 first registered on ClinicalTrials.gov between 1 January 2020 and 1 July 2020. We systematically searched for trial results, reported through 15 May 2023, in scientific publications, preprints and ClinicalTrials.gov. We assessed the achieved trial enrolment, trial discontinuation (reaching <90% of target enrolment), and whether the primary outcome had been changed as compared with the initial protocol registration.

Results: The 775 clinical trials included in the analysis planned to enrol 238 933 (median (IQR) 120 (60, 304) patients; 355 (46%) of the trials had reported results, and 283 (36%) were published in a scientific journal. In the reported trials, the total enrolment was 95 332 (median (IQR) 105 (45, 222) patients. 186 (24%) trials were completed, and 169 (22%) trials were discontinued, with slow recruitment being the most stated reason for discontinuation (9% of all trials, although 30% of the discontinued trials did not report a reason). 117 (33%) of the reported trials had changed their primary outcome. In total, 157 (20%) trials were completed and published in a scientific journal, of which 105 enrolled ≥100 patients and 103 had not changed the primary outcome. 63 completed and published trials enrolled ≥100 patients and had not changed the primary outcome.

Conclusions: Most clinical trials of COVID-19 registered at ClinicalTrials.gov during the first 6 months of the pandemic remained unreported or had been discontinued. Many of the trials whose results had been reported enrolled few patients and changed the primary outcome after trial registration.

Keywords: COVID-19; Clinical Trial; Randomized Controlled Trial; Scientific integrity review.