Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019

Objectives To describe the extent to which pragmatic trials underachieved or overachieved their target sample sizes, examine explanations and identify characteristics associated with under-recruitment and over-recruitment.Study design and setting Secondary analysis of an existing database of primary...

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Main Authors: Karla Hemming, Monica Taljaard, Charles Weijer, Kelly Carroll, Stuart G Nicholls, Pascale Nevins, Yongdong Ouyang
Format: Article
Language:English
Published: BMJ Publishing Group 2022-12-01
Series:BMJ Open
Online Access:https://bmjopen.bmj.com/content/12/12/e067656.full
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author Karla Hemming
Monica Taljaard
Charles Weijer
Kelly Carroll
Stuart G Nicholls
Pascale Nevins
Yongdong Ouyang
author_facet Karla Hemming
Monica Taljaard
Charles Weijer
Kelly Carroll
Stuart G Nicholls
Pascale Nevins
Yongdong Ouyang
author_sort Karla Hemming
collection DOAJ
description Objectives To describe the extent to which pragmatic trials underachieved or overachieved their target sample sizes, examine explanations and identify characteristics associated with under-recruitment and over-recruitment.Study design and setting Secondary analysis of an existing database of primary trial reports published during 2014–2019, registered in ClinicalTrials.gov, self-labelled as pragmatic and with target and achieved sample sizes available.Results Of 372 eligible trials, the prevalence of under-recruitment (achieving <90% of target sample size) was 71 (19.1%) and of over-recruitment (>110% of target) was 87 (23.4%). Under-recruiting trials commonly acknowledged that they did not achieve their targets (51, 71.8%), with the majority providing an explanation, but only 11 (12.6%) over-recruiting trials acknowledged recruitment excess. The prevalence of under-recruitment in individually randomised versus cluster randomised trials was 41 (17.0%) and 30 (22.9%), respectively; prevalence of over-recruitment was 39 (16.2%) vs 48 (36.7%), respectively. Overall, 101 025 participants were recruited to trials that did not achieve at least 90% of their target sample size. When considering trials with over-recruitment, the total number of participants recruited in excess of the target was a median (Q1–Q3) 319 (75–1478) per trial for an overall total of 555 309 more participants than targeted. In multinomial logistic regression, cluster randomisation and lower journal impact factor were significantly associated with both under-recruitment and over-recruitment, while using exclusively routinely collected data and educational/behavioural interventions were significantly associated with over-recruitment; we were unable to detect significant associations with obtaining consent, publication year, country of recruitment or public engagement.Conclusions A clear explanation for under-recruitment or over-recruitment in pragmatic trials should be provided to encourage transparency in research, and to inform recruitment to future trials with comparable designs. The issues and ethical implications of over-recruitment should be more widely recognised by trialists, particularly when designing cluster randomised trials.
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spelling doaj-art-f5394652646a4990bb486e7249c1b25a2025-08-20T02:27:00ZengBMJ Publishing GroupBMJ Open2044-60552022-12-01121210.1136/bmjopen-2022-067656Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019Karla Hemming0Monica Taljaard1Charles Weijer2Kelly Carroll3Stuart G Nicholls4Pascale Nevins5Yongdong Ouyang6Institute of Applied Health Research, University of Birmingham, Birmingham, UK11 School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, CanadaDepartments of Medicine, Epidemiology & Biostatistics, and Philosophy, Western University, London, Ontario, CanadaClinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canadapostdoctoral fellowDepartment of Chemistry and Biomolecular Sciences, University of Ottawa Faculty of Science, Ottawa, Ontario, CanadaClinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, CanadaObjectives To describe the extent to which pragmatic trials underachieved or overachieved their target sample sizes, examine explanations and identify characteristics associated with under-recruitment and over-recruitment.Study design and setting Secondary analysis of an existing database of primary trial reports published during 2014–2019, registered in ClinicalTrials.gov, self-labelled as pragmatic and with target and achieved sample sizes available.Results Of 372 eligible trials, the prevalence of under-recruitment (achieving <90% of target sample size) was 71 (19.1%) and of over-recruitment (>110% of target) was 87 (23.4%). Under-recruiting trials commonly acknowledged that they did not achieve their targets (51, 71.8%), with the majority providing an explanation, but only 11 (12.6%) over-recruiting trials acknowledged recruitment excess. The prevalence of under-recruitment in individually randomised versus cluster randomised trials was 41 (17.0%) and 30 (22.9%), respectively; prevalence of over-recruitment was 39 (16.2%) vs 48 (36.7%), respectively. Overall, 101 025 participants were recruited to trials that did not achieve at least 90% of their target sample size. When considering trials with over-recruitment, the total number of participants recruited in excess of the target was a median (Q1–Q3) 319 (75–1478) per trial for an overall total of 555 309 more participants than targeted. In multinomial logistic regression, cluster randomisation and lower journal impact factor were significantly associated with both under-recruitment and over-recruitment, while using exclusively routinely collected data and educational/behavioural interventions were significantly associated with over-recruitment; we were unable to detect significant associations with obtaining consent, publication year, country of recruitment or public engagement.Conclusions A clear explanation for under-recruitment or over-recruitment in pragmatic trials should be provided to encourage transparency in research, and to inform recruitment to future trials with comparable designs. The issues and ethical implications of over-recruitment should be more widely recognised by trialists, particularly when designing cluster randomised trials.https://bmjopen.bmj.com/content/12/12/e067656.full
spellingShingle Karla Hemming
Monica Taljaard
Charles Weijer
Kelly Carroll
Stuart G Nicholls
Pascale Nevins
Yongdong Ouyang
Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019
BMJ Open
title Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019
title_full Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019
title_fullStr Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019
title_full_unstemmed Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019
title_short Reporting of and explanations for under-recruitment and over-recruitment in pragmatic trials: a secondary analysis of a database of primary trial reports published from 2014 to 2019
title_sort reporting of and explanations for under recruitment and over recruitment in pragmatic trials a secondary analysis of a database of primary trial reports published from 2014 to 2019
url https://bmjopen.bmj.com/content/12/12/e067656.full
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