J Clin Epidemiol. 2023 Aug 25:S0895-4356(23)00216-0. doi: 10.1016/j.jclinepi.2023.08.011. Online ahead of print.
ABSTRACT
OBJECTIVE: Preprints became a major source of research communication during the COVID-19 pandemic. We aimed to evaluate whether summary treatment effect estimates differ between preprint and peer-reviewed journal trials.
STUDY DESIGN AND SETTING: A meta-epidemiological study. Data were derived from the COVID-NMA living systematic review (covid-nma.com) up to July 20, 2022. We identified all meta-analyses evaluating pharmacological treatments vs. standard of care/placebo for patients with COVID-19 that included at least one preprint and one peer-reviewed journal article. Difference in effect estimates between preprint and peer-reviewed journal trials were estimated by the ratio of odds ratio (ROR); ROR < 1 indicated larger effects in preprint trials.
RESULTS: Thirty-seven meta-analyses including 114 trials (44 preprints, 70 peer-reviewed publications) were selected. The median number of RCTs per meta-analysis was 2 (IQR, 2-4; maximum, 11), median sample size of RCTs was 199 (IQR, 99-478). Overall, there was no statistically significant difference in summary effect estimates between preprint and peer-reviewed journal trials (ROR, 0.88; 95% CI, 0.71-1.09; I2 = 17.8%; τ2= 0.06).
CONCLUSION: We did not find an important difference between summary treatment effects of preprints and summary treatment effects of peer-reviewed publications. Systematic reviewers and guideline developers should assess preprint inclusion individually, accounting for risk of bias and completeness of reporting.
PMID:37634703 | DOI:10.1016/j.jclinepi.2023.08.011
