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Missing clinical trial data: the knowledge gap in the safety of potential COVID-19 drugs

By Florence Rodgers, Toby Pepperrell, Sarai Mirjam Keestra, Victoria Pilkington

Posted 03 Jun 2020
medRxiv DOI: 10.1101/2020.05.30.20117523

Abstract Objectives: Several drugs are being repurposed for the treatment of the coronavirus disease 2019 (COVID-19) pandemic based on in vitro or early clinical findings. As these drugs are being used in varied regimens and dosages, it is important to enable synthesis of existing safety data from clinical trials. However, availability of safety information is limited by a lack of timely reporting of clinical trial results on public registries or through academic publication. We aimed to analyse the knowledge gap in safety data by quantifying the number of missing clinical trial results for drugs potentially being repurposed for COVID-19. Design: ClinicalTrials.gov was searched for 19 drugs that have been identified as potential treatments for COVID-19. Relevant clinical trials for any prior indication were listed by identifier (NCT number) and checked for timely result reporting (within 395 days of the primary completion date). Additionally, PubMed and Google Scholar were searched using the NCT number to identify publications of results not listed on the registry. A second, blinded search of 10% of trials was conducted to assess reviewer concordance. Results: Of 3754 completed trials, 1516 (40.4%) did not post results on ClinicalTrials.gov or in the academic literature. 1172 (31.2%) completed trials had tabular results on ClinicalTrials.gov. A further 1066 (28.4%) completed trials had results from the literature search, but did not report results on ClinicalTrials.gov. Key drugs missing clinical trial results include hydroxychloroquine (37.0% completed trials unreported), favipiravir (77.8%) and lopinavir (40.5%). Conclusion: There is an important evidence gap for the safety of drugs being repurposed for COVID-19. This uncertainty could cause a large burden of additional morbidity and mortality during the pandemic. We recommend caution in experimental drug use for non-severe disease and urge clinical trial sponsors to report missing results retrospectively.

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