Comparison of effect estimates between preprints and peer-reviewed publications: a meta-epidemiological study of COVID-19 trials

Oral
2023 London
Davidson M1, Evrenoglou T1, Graña C2, Chaimani A3, Boutron I2
1Université Paris Cité and Université Sorbonne Paris Nord, Inserm, INRAE, Center for Research in Epidemiology and Statistics (CRESS), F-75004 Paris
2Université Paris Cité and Université Sorbonne Paris Nord, Inserm, INRAE, Center for Research in Epidemiology and Statistics (CRESS), F-75004 Paris; Centre d’Epidémiologie Clinique, AP-HP, Hôpital Hôtel Dieu, F-75004, Paris; Cochrane France, Paris
3Université Paris Cité and Université Sorbonne Paris Nord, Inserm, INRAE, Center for Research in Epidemiology and Statistics (CRESS), F-75004 Paris; Cochrane France, Paris
Background: Preprints have emerged as a major source of research communication during the COVID-19 pandemic. However, questions were raised concerning the reliability of their results.

Objectives: To evaluate whether effect estimates differ between preprint and peer-reviewed journal randomised controlled trials (RCTs).

Methods: Data were derived from the COVID-NMA (covid-nma.com) initiative, a living systematic review of RCTs evaluating preventive interventions, treatments and vaccines for COVID-19. Meta-analyses with at least one preprint and one peer-reviewed journal article evaluating pharmacological treatments vs. standard of care/placebo were included up to July 20, 2022. Predefined COVID-NMA ‘critical outcomes’ at 28 days were considered. A meta-epidemiological analysis estimated the difference in effect estimates [expressed as the ratio of odds ratio (ROR)] between preprint and peer-reviewed journal RCTs. An ROR of