Reporting missing participant data in randomised trials: systematic survey of the methodological literature and a proposed guide
Open accessAbstract
Objectives: We conducted a systematic survey of the methodological literature to identify recommended approaches for how and what randomised clinical trial (RCT) authors should report on missing participant data and, on the basis of these approaches, to propose guidance for RCT authors. Methods: We defined missing participant data (MPD) as missing outcome data for trial participants. We considered both categorical and continuous outcome data. We searched MEDLINE and the Cochrane Methodology Register for articles in which authors proposed approaches to reporting MPD from RCTs. We selected eligible articles independently and in duplicate and extracted data in duplicate. Using an iterative process of discussion and revisions, we used the findings to develop guidance. Results: Of 10 501 unique citations identified, 13 articles reporting on 10 approaches proved eligible. The identified approaches recommend reporting the following aspects (from most to least frequently recommended): number of participants with MPD (n=10), reasons for MPD (n=7), methods used to handle MPD in the analysis (n=4), flow of participants (n=3), pattern of missingness (eg, whether at random) (n=3), differences in rates of MPD between trial arms (n=2), differences between participants with and without MPD (n=2), results of any sensitivity analyses (n=2), implication of MPD on interpreting the results (n=2) and methods used to prevent missing data (n=1). We propose a guide with nine items related to reporting the number, reasons, patterns, analytical methods and interpretation of MPD. Conclusions: Most identified approaches invite trial authors to report the extent of MPD and the underlying reasons. Fewer approaches focus on reporting missingness patterns, methods for handling MPD and implications of MPD on results. Our proposed guidance could help RCT authors to better report, and readers to better identify participants with missing data.
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Some reasons for missingness could be related to the treatment allocation, prognostic factors, or a particular adverse event or health outcome.
“Some reasons for missingness could be related to the treatment allocation, prognostic factors, or a particular adverse event or health outcome.427”
From SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials (2025) · cites this paper as [427]
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- Authors
- Akl, E. A., Shawwa, K., Kahale, L. A., Agoritsas, T., Brignardello-Petersen, R., Busse, J. W., Carrasco–Labra, A., Ebrahim, S., Johnston, B. C., Neumann, I., Sola, I., Sun, X., Vandvik, P., Zhang, Y., Alonso-Coello, P., & Guyatt, G. H.
- Affiliations
- McMaster University (CA)
- American University of Beirut (LB)
- Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada
- Hospital for Sick Children (CA)
- University of Toronto (CA)
- Pontificia Universidad Católica de Chile (CL)
- Iberoamerican Cochrane Centre, Biomedical Research Institute Sant Pau-CIBER of Epidemiology and Public Health (CIBERESP- IIB Sant Pau), Barcelona, Spain
- Sichuan University (CN)
- Innlandet Hospital Trust (NO)
- Corresponding author
- Akl, Elie A
- ORCID
- Venue
- BMJ Open
- Publisher
- BMJ
- Published
- 2015-12
- Volume
- 5
- Issue
- 12
- Pages
- e008431
- ISSN
- 2044-6055 (ISSN-L)
- PMC
- PMC4710817
- OpenAlex
- W2258698375
- Cited by
- 52
- References
- 26
- Citations by year
- 2026: 1 · 2025: 5 · 2024: 10 · 2023: 4 · 2022: 7 · 2021: 3 · 2020: 4 · 2019: 7 · 2018: 5 · 2017: 3 · 2016: 3
- FWCI
- 3.35
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- cc-by-nc
- Locations
- BMJ Open (publishedVersion, cc-by-nc)
- PubMed Central (publishedVersion, cc-by-nc)
- PubMed (publishedVersion)
- Archive ouverte UNIGE (University of Geneva) (publishedVersion, other-oa)
- Dipòsit Digital de Documents de la UAB (Universitat Autònoma de Barcelona) (submittedVersion, cc-by-nc)
- Universidad de Chile (submittedVersion, cc-by-nc-nd)
- Archive ouverte UNIGE (University of Geneva) (submittedVersion, cc-by)
- Topics
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
- Keywords
- randomized controlled trials, reporting guidelines, missingness patterns, missing data handling, sensitivity analysis
- MeSH terms
- Data Accuracy, Humans, Patient Dropouts, Research Design, Bias, Randomized Controlled Trials as Topic, Guidelines as Topic
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