Pooled evidence precision of clinical trials on hydroxychloroquine for Covid-19 treatment was stabilized eight months after the outbreak

OBJECTIVE At the beginning of 2020, hydroxychloroquine showed promising in vitro activity for Covid-19 and several studies were oriented to assess its safety and efficacy. However, after a few months, hydroxychloroquine has proved ineffective. The randomized controlled trials (RCTs) developed quickly and in different settings represent the scientific community’s capacity to assess drug repositioning effectiveness during a sanitary crisis. Therefore, a critical evaluation of the evidence generated can guide future efforts in analogous situations. We aimed to analyze the RCTs assessing the efficacy of hydroxychloroquine in treating Covid-19, describe their internal validity and power, and evaluate their contribution to the precision of the combined evidence for assessing the mortality outcome. STUDY DESIGN AND SETTINGS This meta-research included RCTs assessing hydroxychloroquine to treat patients diagnosed with Covid-19. It was part of an umbrella systematic review of methods/meta-research (PROSPERO: CRD42022360331) that included a comprehensive search in MEDLINE, EMBASE, Cochrane Library, and the Latin America Database - Lilacs. We retrieved studies published until January 10th, 2022. The risk of bias was assessed using Risk of Bias (RoB) 2.0. We analyzed methodology of the studies, precision and random error change through time from pooled evidence, study comparators, patient important outcome, power in different magnitude of effects proxy. RESULTS A total of 22 RCT were included, from that 17 (77%) assessed hospitalized patients and five (23%) outpatients setting. Mortality was related as primary endpoint in only 4 studies, however half of the studies included composite endpoints including mortality as a component. The internal validity analysis using RoB2 found that eight studies (36%) had a high risk of bias. Only one study had sufficient power to evaluate a moderate magnitude of effect (RR = 0,7 on mortality). The standard error to evaluate efficacy on mortality did not change appreciably after October 2020. From Oct 2020 to Dec 2021, 18 additional studies were published with 2,429 patients recruited. CONCLUSION This meta-research highlights the impact that collaborative, and network scientific research have on informing clinical decision-making. Duplicate efforts create research waste as precision analysis shows that after October 2020, there was not appreciably changes in the precision of the pooled RCT evidence to estimate the hydroxychloroquine effect on mortality. What is new? ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced are available online as all studies included were published