Use of methods for specifying the target difference in randomised controlled trial sample size calculations: Two surveys of trialists' practice
Use of methods for specifying the target difference in randomised controlled trial sample size calculations: Two surveys of trialists' practice
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DOI：
10.1177/1740774514521907
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发表时间：
2014-06-01
期刊：
影响因子：
2.7
通讯作者：
Vale, Luke D.
中科院分区：
文献类型：
--
作者：
Cook, Jonathan A.;Hislop, Jennifer M.;Vale, Luke D.
随机对照试验（RCT）设计的核心是计算所需的受试者人数。这通常是通过指定目标差异来实现的，这使得试验能够识别特定大小的差异（如果存在的话）。已经提出了七种方法来正式确定目标差异应该是什么。然而，在实践中，这可能是出于方便或其他一些非正式的原因。目前还不清楚如何知道trialist社区是这些正式的methods.Purpose或他们是否used.Purpose要确定目前的做法，关于规格的目标差异，通过调查trialists.Methods进行了两项调查：（1）成员的社会临床试验（SCT）：参与者被邀请完成一项在线调查，通过社会的电子邮件分发列表。受访者被问及他们的认识，使用和愿意推荐的方法;（2）领先的英国和爱尔兰的试验：调查被发送到英国临床研究协作注册的临床试验单位，医学研究理事会英国中心的试验方法研究，和研究设计服务的国家卫生研究所。这项调查还包括有关最近的审判开发的受访者的group.ResultsSurvey 1的问题：SCT成员的电子邮件分发列表中的1182名成员，收到180个答复（15%）。方法的认识范围从69（38%）的卫生经济学方法的162（90%）的试点研究。在使用过特定方法的人中，推荐的意愿从征求意见方法的56%到循证方法的89%不等。调查2：在发出的61份调查中，收到了34份（56%）答复。对方法的认识从33（97%）的循证和试点方法审查到14（41%）的分配方法。用户推荐意愿最高的是锚方法（87%）。根据最近的试验，目标差异通常是利益相关者群体认为重要的差异，考虑到所评估的干预措施，大多数情况下也被视为现实差异，有时导致可实现的样本量。结论在实践中存在很大的差异，意识，使用和意愿，建议方法有很大的不同。研究结果支持样本量计算是一个比试验报告和方案更复杂的过程的观点。关于样本量估计方法的指导可提高对适当正式方法的认识和使用。
Background Central to the design of a randomised controlled trial (RCT) is a calculation of the number of participants needed. This is typically achieved by specifying a target difference, which enables the trial to identify a difference of a particular magnitude should one exist. Seven methods have been proposed for formally determining what the target difference should be. However, in practice, it may be driven by convenience or some other informal basis. It is unclear how aware the trialist community is of these formal methods or whether they are used.Purpose To determine current practice regarding the specification of the target difference by surveying trialists.Methods Two surveys were conducted: (1) Members of the Society for Clinical Trials (SCT): participants were invited to complete an online survey through the society's email distribution list. Respondents were asked about their awareness, use of, and willingness to recommend methods; (2) Leading UK- and Ireland-based trialists: the survey was sent to UK Clinical Research Collaboration registered Clinical Trials Units, Medical Research Council UK Hubs for Trial Methodology Research, and the Research Design Services of the National Institute for Health Research. This survey also included questions about the most recent trial developed by the respondent's group.ResultsSurvey 1: Of the 1182 members on the SCT membership email distribution list, 180 responses were received (15%). Awareness of methods ranged from 69 (38%) for health economic methods to 162 (90%) for pilot study. Willingness to recommend among those who had used a particular method ranged from 56% for the opinion-seeking method to 89% for the review of evidence-base method. Survey 2: Of the 61 surveys sent out, 34 (56%) responses were received. Awareness of methods ranged from 33 (97%) for the review of evidence-base and pilot methods to 14 (41%) for the distribution method. The highest level of willingness to recommend among users was for the anchor method (87%). Based upon the most recent trial, the target difference was usually one viewed as important by a stakeholder group, mostly also viewed as a realistic difference given the interventions under evaluation, and sometimes one that led to an achievable sample size.Limitations The response rates achieved were relatively low despite the surveys being short, well presented, and having utilised reminders.Conclusion Substantial variations in practice exist with awareness, use, and willingness to recommend methods varying substantially. The findings support the view that sample size calculation is a more complex process than would appear to be the case from trial reports and protocols. Guidance on approaches for sample size estimation may increase both awareness and use of appropriate formal methods.