ArticleBMJ (Clinical research ed.)2008
Discrepancies in sample size calculations and data analyses reported in randomised trials: comparison of publications with protocols.
Article in BMJ (Clinical research ed.), 2008. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 80 papers, 10 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
80 citing papers in PubMed, 10 syntheses or guidelines pooled it.
- Estimating the prevalence of discrepancies between study registrations and publications: a systematic review and meta-analyses.BMJ open · 2023Pooled it
- Citicoline for treating people with acute ischemic stroke.The Cochrane database of systematic reviews · 2020Pooled it
- A systematic review of comparisons between protocols or registrations and full reports in primary biomedical research.BMC medical research methodology · 2018Pooled it
- Sample size calculations in pediatric clinical trials conducted in an ICU: a systematic review.Trials · 2014Pooled it
- Evidence for the selective reporting of analyses and discrepancies in clinical trials: a systematic review of cohort studies of clinical trials.PLoS medicine · 2014Pooled it
- Systematic evaluation of the patient-reported outcome (PRO) content of clinical trial protocols.PloS one · 2014Pooled it
- SPIRIT 2013 statement: defining standard protocol items for clinical trials.Annals of internal medicine · 2013 · on this mapGuideline
- The assessment of the quality of reporting of meta-analyses in diagnostic research: a systematic review.BMC medical research methodology · 2011Pooled it
- The influence of study characteristics on reporting of subgroup analyses in randomised controlled trials: systematic review.BMJ (Clinical research ed.) · 2011Pooled it
- Modified intention to treat reporting in randomised controlled trials: systematic review.BMJ (Clinical research ed.) · 2010Pooled it
- Doxylamine-pyridoxine for nausea and vomiting of pregnancy randomized placebo controlled trial: Prespecified analyses and reanalysis.PloS one · 2018Trial
- Deep learning in rib fracture imaging: study quality assessment using the Must AI Criteria-10 (MAIC-10) checklist for artificial intelligence in medical imaging.Insights into imaging · 2025Article
- SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials.BMJ (Clinical research ed.) · 2025Article
- Does renal denervation require cardiovascular outcome-driven data?Hypertension research : official journal of the Japanese Society of Hypertension · 2024Review
- Overall Reporting Quality of Randomized Controlled Trials of Acupuncture for Knee Osteoarthritis: A Systematic Review.Journal of pain research · 2024Article
- Reporting Quality of Endoscopic Colorectal Cancer Screening Randomized Controlled Trials: Adherence to Recommendations and Interventions.Gastro hep advances · 2024Review
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- Subgroup Analysis in Pulmonary Hypertension-Specific Therapy Clinical Trials: A Systematic Review.Journal of personalized medicine · 2022Review
- Review of pragmatic trials found that multiple primary outcomes are common but so too are discrepancies between protocols and final reports.Journal of clinical epidemiology · 2022Review
20 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
5 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveTo evaluate how often sample size calculations and methods of statistical analysis are pre-specified or changed in randomised trials.
designRetrospective cohort study. Data source Protocols and journal publications of published randomised parallel group trials initially approved in 1994-5 by the scientific-ethics committees for Copenhagen and Frederiksberg, Denmark (n=70).
main outcome measureProportion of protocols and publications that did not provide key information about sample size calculations and statistical methods; proportion of trials with discrepancies between information presented in the protocol and the publication.
resultsOnly 11/62 trials described existing sample size calculations fully and consistently in both the protocol and the publication. The method of handling protocol deviations was described in 37 protocols and 43 publications. The method of handling missing data was described in 16 protocols and 49 publications. 39/49 protocols and 42/43 publications reported the statistical test used to analyse primary outcome measures. Unacknowledged discrepancies between protocols and publications were found for sample size calculations (18/34 trials), methods of handling protocol deviations (19/43) and missing data (39/49), primary outcome analyses (25/42), subgroup analyses (25/25), and adjusted analyses (23/28). Interim analyses were described in 13 protocols but mentioned in only five corresponding publications.
conclusionWhen reported in publications, sample size calculations and statistical methods were often explicitly discrepant with the protocol or not pre-specified. Such amendments were rarely acknowledged in the trial publication. The reliability of trial reports cannot be assessed without having access to the full protocols.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.