The majority of observational studies in leading peer-reviewed medicine journals are not registered and do not have a publicly accessible protocol: a scoping review

Leducq, Sophie; Zaki, Faaris; Hollestein, Loes M.; Apfelbacher, Christian; Ponna, Nikhil Prasanna; Mazmudar, Rishabh; Gran, Sonia

Abstract

Objectives
Observational studies are not subject to the same requirements as randomized controlled trials, such as registration or publishing a protocol. The aim of this scoping review was to estimate the registration rate of observational studies in leading peer-reviewed medicine journals and to evaluate whether protocols were available in the public domain.

Study Design and Setting
In March 2023, we searched OVID Medline for observational studies published in 2022 in the top five general medicine journals according to impact factor (The Lancet, The British Medical Journal (BMJ), The Journal of the American Medical Association, The New England Journal of Medicine, and Annals of Internal Medicine). We defined an observational study as a cohort study, a case-control study, a cross-sectional study, or a case series. Information on i) the proportion of observational studies that have been registered and ii) the proportion of observational studies that have a protocol available in the public domain was extracted from a random sample of studies.

Results
Our search identified 699 studies; 290 studies were selected as full text, and a random sample of 200 studies was included. For half of the studies, the first author worked at a US institution. Most studies were cohort studies (n = 126, 63.0%) and used administrative healthcare records, electronic healthcare records, and registries. Of the 200 observational studies, 20 (10.0%) were registered. Among those, 14 were prospectively registered. Twenty-four studies (12.0%) had a protocol available in the public domain. Studies that were registered or had a protocol, were more frequently published in the BMJ (n = 12/28, 42.9%), had a first author working in the UK (n = 10/28, 35.7%) and used electronic health care records (n = 13/28, 46.4%) compared to studies with no registration and no protocol.

Conclusion
The rate of prospectively registered observational studies is worryingly low. Prospective registration of observational studies should be encouraged and standardized to ensure transparency in clinical research and reduce research waste.

• Journal Article Type: Review
• Acceptance Date: Mar 25, 2024
• Online Publication Date: Mar 29, 2024
• Publication Date: 2024-06
• Deposit Date: May 22, 2024
• Publicly Available Date: May 24, 2024
• Journal: Journal of Clinical Epidemiology
• Print ISSN: 0895-4356
• Electronic ISSN: 1878-5921
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 170
• Article Number: 111341
• DOI: https://doi.org/10.1016/j.jclinepi.2024.111341
• Keywords: Observational study; Epidemiology; Transparency; Registration; Protocol; Cohort
• Public URL: https://nottingham-repository.worktribe.com/output/35151834
• Publisher URL: https://www.jclinepi.com/article/S0895-4356(24)00096-9/fulltext
• Additional Information: This article is maintained by: Elsevier; Article Title: The majority of observational studies in leading peer-reviewed medicine journals are not registered and do not have a publicly accessible protocol: a scoping review; Journal Title: Journal of Clinical Epidemiology; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.jclinepi.2024.111341; Content Type: article; Copyright: © 2024 The Authors. Published by Elsevier Inc.