ArticleClinical trials (London, England)2018
Are pilot trials useful for predicting randomisation and attrition rates in definitive studies: A review of publicly funded trials.
Article in Clinical trials (London, England), 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 35 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
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
35 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Dropout Rate in Digital Health Interventions for the Prevention of Skin Cancer: Systematic Review, Meta-analysis, and Metaregression.Journal of medical Internet research · 2022Pooled it
- A Mobile Self-Assessment and Referral Platform for Family Caregivers of Individuals With Alzheimer Disease and Related Dementias: Protocol for a Pilot Randomized Controlled Trial.JMIR research protocols · 2026Trial
- Comparison of the analgesic efficacy of superficial and deep serratus anterior plane blocks in patients undergoing breast cancer surgery: a prospective randomized single blind study.BMC anesthesiology · 2026Trial
- Cognitive Behavioral Therapy for Insomnia May Improve Sleep and Pain in Crohn's Disease: A Waitlist Control Pilot Trial.Inflammatory bowel diseases · 2026Trial
- A technology-based intervention to reduce alcohol use after metabolic and bariatric surgery: feasibility, acceptability, and preliminary outcomes.Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery · 2025Trial
- Extracorporeal Shockwave Therapy for Diabetes Related Foot Ulcers: A Pilot Three-Arm Double-Blinded Randomised Controlled Trial.International wound journal · 2025Trial
- Utilizing primary care to engage underserved patients in a psychological intervention for chronic pain.Primary health care research & development · 2024Trial
- Preliminary Effectiveness of mHealth App-Based Pelvic Floor Muscle Training among Pregnant Women to Improve Their Exercise Adherence: A Pilot Randomised Control Trial.International journal of environmental research and public health · 2022Trial
- Lifestyle Matters Randomized Controlled Trial of a Preventive Health Intervention for Older People: Qualitative Sub Study with Participants and Intervention Facilitators.Clinical interventions in aging · 2020Trial
- Trial
- Recruitment of individuals into a type 2 diabetes prevention program: the relative effectiveness and cost of different recruitment strategies used for the randomised controlled trial testing an Australian Lifestyle Change Program (AUS2PREVENT).Pilot and feasibility studies · 2026Article
- A Need for Strategies to Reduce Alcohol Use After Metabolic and Bariatric Surgery: Technology-Based Intervention and Study Protocol for a Pilot Randomized Controlled Trial.JMIR research protocols · 2026Article
- Addressing burn-injury stigma through health education and communication campaign in Pakistan: study protocol.Frontiers in public health · 2025Article
- Pilot and feasibility studies in ophthalmology: fundamental keys to success.Eye (London, England) · 2025Article
- Article
- Innovative continuum of care to promote exclusive breast feeding in Pakistan: protocol of a pilot randomised controlled trial.BMJ paediatrics open · 2024Article
- A review of sample sizes for UK pilot and feasibility studies on the ISRCTN registry from 2013 to 2020.Pilot and feasibility studies · 2023Review
- Pilot Trial Characteristics, Postpilot Design Modifications, and Feasibility of Full-Scale Trials.JAMA network open · 2023Article
- Results from a randomised controlled pilot study of the Better Conversations with Primary Progressive Aphasia (BCPPA) communication partner training program for people with PPA and their communication partners.Pilot and feasibility studies · 2023Article
- Pilot and feasibility studies: extending the conceptual framework.Pilot and feasibility studies · 2023Article
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
Abstract
BACKGROUND/
aimsExternal pilot trials are recommended for testing the feasibility of main or confirmatory trials. However, there is little evidence that progress in external pilot trials actually predicts randomisation and attrition rates in the main trial. To assess the use of external pilot trials in trial design, we compared randomisation and attrition rates in publicly funded randomised controlled trials with rates in their pilots.
methodsRandomised controlled trials for which there was an external pilot trial were identified from reports published between 2004 and 2013 in the Health Technology Assessment Journal. Data were extracted from published papers, protocols and reports. Bland-Altman plots and descriptive statistics were used to investigate the agreement of randomisation and attrition rates between the full and external pilot trials.
resultsOf 561 reports, 41 were randomised controlled trials with pilot trials and 16 met criteria for a pilot trial with sufficient data. Mean attrition and randomisation rates were 21.1% and 50.4%, respectively, in the pilot trials and 16.8% and 65.2% in the main. There was minimal bias in the pilot trial when predicting the main trial attrition and randomisation rate. However, the variation was large: the mean difference in the attrition rate between the pilot and main trial was -4.4% with limits of agreement of -37.1% to 28.2%. Limits of agreement for randomisation rates were -47.8% to 77.5%.
conclusionResults from external pilot trials to estimate randomisation and attrition rates should be used with caution as comparison of the difference in the rates between pilots and their associated full trial demonstrates high variability. We suggest using internal pilot trials wherever appropriate.
Indexed as
Identifiers
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.