Three out of four published systematic reviews on COVID-19 treatments were not registered and one-third of those registered were published: a meta-research study

Objectives: The aim of this study is to describe (1) registered and (2) published systematic reviews (SRs) on COVID-19 treatments, and to analyze (3) the proportion of publications among registered SRs and (4) the proportion of registrations among published SRs.Study Design and Setting: This meta-research study (CRD42021240423) is part of CEOsys (http://www.covid-evidenz.de/). Two re-viewers identified protocols in PROSPERO (registered January 2020 to September 2020) and SRs published as preprint or peer-reviewed article in L center dot OVE (Living OVerview of the Evidence) COVID-19 (by May 2021). SRs of all types assessing COVID-19 treatments in hu-mans were included.Results: We included 239 PROSPERO protocols and 346 SRs published in L center dot OVE. In both samples, the affiliation of the correspond-ing author with an Asian institution, standard SR as review type, and meta-analysis as synthesis method were the most frequent charac-teristics. Living SRs made up <= 10%. A total of 71 of 239 (29.7%) PROSPERO protocols were published as SR by February 2022, that is, after at least 17 months of follow-up (25 of 71 as preprints, 35.2%). In L center dot OVE, 261 of 346 (75.4%) SRs published by May 2021 were not registered in PROSPERO.Conclusion: Overall, one-third PROSPERO protocols were published and three-fourth published SRs were not registered. We strongly encourage authors to register and publish their SRs promptly to reduce research waste and to allocate resources efficiently during the pandemic and beyond. (c) 2022 Elsevier Inc. All rights reserved.