Department of Chemistry and Biomolecular Sciences, University of Ottawa Faculty of Science, Ottawa, Ontario, Canada.
Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
BMJ Open. 2022 Dec 9;12(12):e067656. doi: 10.1136/bmjopen-2022-067656.
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.
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.
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.
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.
描述实用临床试验未达到或超过目标样本量的程度，探讨解释并确定与招募不足和招募过度相关的特征。
对 2014 年至 2019 年期间在 ClinicalTrials.gov 注册的、自我标记为实用且具有目标和实际样本量的主要试验报告的现有数据库进行二次分析。
在 372 项合格试验中，招募不足（达到目标样本量的<90%）的比例为 71 项（19.1%），招募过度（超过目标的 110%）的比例为 87 项（23.4%）。未招募到足够数量的试验通常承认未达到目标（51 项，71.8%），其中大多数提供了解释，但只有 11 项（12.6%）过度招募的试验承认招募过多。个体随机试验和集群随机试验中招募不足的比例分别为 41 项（17.0%）和 30 项（22.9%）；招募过度的比例分别为 39 项（16.2%）和 48 项（36.7%）。总体而言，有 101025 名参与者被招募到未达到至少 90%目标样本量的试验中。在考虑过度招募的试验时，每个试验招募的超过目标人数中位数（Q1-Q3）为 319（75-1478），总共有 555309 名参与者超过目标。在多项逻辑回归中，集群随机化和较低的期刊影响因子与招募不足和过度招募均显著相关，而仅使用常规收集的数据和教育/行为干预与过度招募显著相关；我们未能检测到与获得同意、出版年份、招募国家或公众参与有关的显著关联。
实用临床试验中应明确解释招募不足或过度招募的原因，以鼓励研究的透明度，并为未来具有类似设计的试验提供信息。试验者应更广泛地认识到过度招募的问题和伦理影响，特别是在设计集群随机试验时。
