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

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

doi:10.1016/j.jclinepi.2024.111341

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

J Clin Epidemiol. 2024 Mar 29:111341. doi: 10.1016/j.jclinepi.2024.111341. Online ahead of print.

Authors

Sophie Leducq¹, Faaris Zaki², Loes M Hollestein³, Christian Apfelbacher⁴, Nikhil Prasanna Ponna⁵, Rishabh Mazmudar⁶, Sonia Gran⁷

Affiliations

¹ Centre of Evidence Based Dermatology, School of Medicine, Faculty of Medicine & Health Sciences, University of Nottingham, United Kingdom; Department of Dermatology, University Hospital of Tours, Tours, France; INSERM, SPHERE, U1246, Tours University, Nantes University, Tours, France. Electronic address: sophie.leducq@univ-tours.fr.
² Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom.
³ Department of Research, Netherlands Comprehensive Cancer Organisation (IKNL), Utrecht, The Netherlands; Department of Dermatology, Erasmus University Medical Center, Rotterdam, The Netherlands.
⁴ Department of Dermatology, Erasmus University Medical Center, Rotterdam, The Netherlands; Institute of Social Medicine and Health Systems Research, Otto von Guericke University Magdeburg, Magdeburg, Germany.
⁵ Faculty of Medicine & Health Sciences, University of Nottingham, United Kingdom.
⁶ Case Western Reserve University School of Medicine, Cleveland, OH, United States of America.
⁷ Centre of Evidence Based Dermatology, School of Medicine, Faculty of Medicine & Health Sciences, University of Nottingham, United Kingdom.

PMID: 38556099
DOI: 10.1016/j.jclinepi.2024.111341

Abstract

Objectives: Observational studies are not subject to the same requirements as randomised controlled trials such as 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, 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, case-control study, cross-sectional study, or 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 were included. For half of the studies, the first author worked in an USA 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 1^st author working in the UK (n=10/28, 35.1%) and used electronic health 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 wastage.

Keywords: epidemiology; observational study; protocol; registration; transparency.

Publication types

Review