Comparison of preprints and final journal publications from COVID-19 Studies: Discrepancies in results reporting and spin in interpretation
Authors: Bero Lisa , Lawrence Rosa , Leslie Louis , Chiu Kellia , McDonald Sally , J Page Matthew , Grundy Quinn , Parker Lisa , L Boughton Stephanie , J Kirkham Jamie , Featherstone Robin 
Published: April 2021

ABSTRACTObjectiveTo compare results reporting and the presence of spin in COVID-19 study preprints with their finalized journal publicationsDesignCross-sectionalSettingInternational medical literatureParticipantsPreprints and final journal publications of 67 interventional and observational studies of COVID-19 treatment or prevention from the Cochrane COVID-19 Study Register published between March 1, 2020 and October 30, 2020Main outcome measuresStudy characteristics and discrepancies in 1) Results reporting (number of outcomes, outcome descriptor, measure (e.g., PCR test), metric (e.g., mean change from baseline), assessment time point (e.g., 1 week post treatment), data reported (e.g., effect estimate and measures of precision), reported statistical significance of result, type of statistical analysis (e.g., chi-squared test), subgroup analyses (if any), whether outcome was identified as primary or secondary and 2) Spin (reporting practices that distort the interpretation of results so that results are viewed more favorably).ResultsOf 67 included studies, 23 (34%) had no discrepancies in results reporting between preprints and journal publications. Fifteen (22%) studies had at least one outcome that was included in the journal publication, but not the preprint; 8 (12%) had at least one outcome that was reported in the preprint only. For outcomes that were reported in both preprints and journals, common discrepancies were differences in numerical values and statistical significance, additional statistical tests and subgroup analyses conducted in journal publications, and longer follow-up times for outcome assessment in journal publications.At least one instance of spin occurred in both preprints and journals in 23 / 67 (34%) studies, the preprint only in 5 (7%) studies, and the journal publications only in 2 (3%) of studies. Spin was removed between the preprint and journal publication in 5/67 (7%) studies; but added in 1/67 (1%) study.ConclusionsThe COVID-19 preprints and their subsequent journal publications were largely similar in reporting of study characteristics, outcomes and spin. All COVID-19 studies published as preprints and journal publications should be critically evaluated for discrepancies and spin.EQUATOR REPORTING GUIDELINESTROBEWhat is already known on this topicSelective and incomplete reporting of results and spin are threats to the trustworthiness and validity of research.These reporting practices could be particularly dangerous for users of COVID-19 research as they can inflate the efficacy of interventions and underestimate harms.Given the high prevalence, visibility, and potentially rapid implementation of COVID-19 research published as preprints, it is important to compare components of results reporting and the presence of spin in COVID-19 studies on treatment or prevention that are published both as preprints and journal publications.What this study addsThis comparison of 67 COVID-19 preprints related to treatment or prevention and their subsequent journal publications found they were largely similar in reporting of study characteristics, components of results reporting and spin in interpretation.Even a few important discrepancies could impact decision making.