Comparison of preprints and their corresponding peer-reviewed publications in the health field: a scoping review

Preprints are becoming more common in the health sciences and allow for instant dissemination of research findings; however, with the risk of compromising quality and transparency. Peer review potentially improves reporting and reduces errors, although its actual impact is not known. The objective of this scoping review was to synthesize evidence comparing preprints in the health areas to their peer-reviewed versions and assess preprint publication rates.

We searched Embase, Medline OVID, Scopus, and Web of Science from inception to July 2024 for studies comparing preprints with their peer-reviewed versions and/or investigating preprint publication rates. Two reviewers independently conducted screening and extracted data on study characteristics, parameters compared, and preprint publication rates. We conducted a narrative synthesis.

We included 40 studies (published 2019-2024; 92% peer-reviewed). The median number of studies analyzed per article was 356 (range: 19-73,256). 42% of preprints were eventually published among 33 studies that reported publication rates (IQR: 22%-67%). Preprint searches routinely started on January 1, 2020, with a median of 24.3 months and a median difference of 11.5 months between preprint and peer-reviewed search end dates. Commonly compared parameters were primary outcomes/endpoints (37%) and sample size (30%), with peer-reviewed articles showing improved reporting for funding (13%), conflicts of interest (13%).

While peer review enhances transparency and methodological reporting (e.g., funding, conflicts of interest), the content, outcomes, and conclusions of health-related preprints remain largely consistent with their peer-reviewed versions. Preprints facilitate rapid knowledge dissemination but may benefit from stricter reporting standards to improve credibility. Future efforts should focus on standardizing preprint policies to bridge quality gaps without delaying access.