BackgroundThe information provided to participants of adaptive platform trials assessing therapies for COVID-19 inpatients is unknown. We aim to evaluate it by reviewing participant information sheets/informed consent forms (PIS/ICFs).MethodsWe searched the Cochrane COVID-19 Study Register and ClinicalTrials.gov (28 March 2022) to identify non-industry-sponsored adaptive platform phase 2+ trials with publicly available protocols and PIS/ICFs, selecting versions closest to the initial one. We assessed the elements of information included in the Good Clinical Practice guidelines and the Declaration of Helsinki as present, absent, or deficient (incompletely described).ResultsWe included PIS/ICFs of 11 trials (ACCORD-2, ACTIV-1IM, Bari-SolidAct, CATALYST, Discovery, HEAL-COVID, ITAC, RECOVERY, REMAP-COVID, Solidarity and TACTIC-R), which were 4-32 pages long (median (md) = 11). Between two and 11 (md = 6) of the 25 different elements of information assessed were omitted or deficiently described in the PIS/ICFs of the 11 trials. Information about providing trial results, investigators’ conflicts of interest, post-study provisions, payment to and anticipated expenses for participants, number of participants, and on whether participants will receive new information that could impact their decision on staying in the trial, were omitted or deficiently described in at least five PIS/ICFs.ConclusionsInvestigators failed to include a few important elements of information in the trial’s PIS/ICF deemed relevant by international standards. In protocols of future trials, investigators should explain why elements of information specified in the Good Clinical Practice guidelines and/or by the Declaration of Helsinki were omitted from the PIS/ICFs.