Cook Jonathan A, Julious Steven A, Sones William, Rothwell Joanne C, Ramsay Craig R, Hampson Lisa V, Emsley Richard, Walters Stephen J, Hewitt Catherine, Bland Martin, Fergusson Dean A, Berlin Jesse A, Altman Doug, Vale Luke D
Centre for Statistics in Medicine, Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK.
Medical Statistics Group, School of Health and Related Research (ScHARR), The University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK.
Trials. 2017 Jun 12;18(1):271. doi: 10.1186/s13063-017-1969-5.
A key step in the design of a randomised controlled trial (RCT) is the estimation of the number of participants needed. By far the most common approach is to specify a target difference and then estimate the corresponding sample size; this sample size is chosen to provide reassurance that the trial will have high statistical power to detect such a difference between the randomised groups (at the planned statistical significance level). The sample size has many implications for the conduct of the study, as well as carrying scientific and ethical aspects to its choice. Despite the critical role of the target difference for the primary outcome in the design of an RCT, the manner in which it is determined has received little attention. This article reports the protocol of the Difference ELicitation in TriAls (DELTA) project, which will produce guidance on the specification and reporting of the target difference for the primary outcome in a sample size calculation for RCTs.
METHODS/DESIGN: The DELTA project has five components: systematic literature reviews of recent methodological developments (stage 1) and existing funder guidance (stage 2); a Delphi study (stage 3); a 2-day consensus meeting bringing together researchers, funders and patient representatives, as well as one-off engagement sessions at relevant stakeholder meetings (stage 4); and the preparation and dissemination of a guidance document (stage 5).
Specification of the target difference for the primary outcome is a key component of the design of an RCT. There is a need for better guidance for researchers and funders regarding specification and reporting of this aspect of trial design. The aim of this project is to produce consensus based guidance for researchers and funders.
随机对照试验（RCT）设计中的关键一步是估计所需的参与者数量。目前最常见的方法是指定一个目标差异，然后估计相应的样本量；选择这个样本量是为了确保试验有足够的统计效力来检测随机分组之间的这种差异（在计划的统计显著性水平上）。样本量对研究的开展有诸多影响，其选择还涉及科学和伦理方面。尽管目标差异在RCT设计中对主要结局起着关键作用，但确定它的方式却很少受到关注。本文报告了“试验中差异引出”（DELTA）项目的方案，该项目将为RCT样本量计算中主要结局的目标差异的设定和报告提供指导。
方法/设计：DELTA项目有五个组成部分：对近期方法学进展的系统文献综述（第1阶段）和现有资助者指南（第2阶段）；一项德尔菲研究（第3阶段）；为期两天的共识会议，召集研究人员、资助者和患者代表，以及在相关利益相关者会议上的一次性参与环节（第4阶段）；以及编写和传播一份指导文件（第5阶段）。
主要结局目标差异的设定是RCT设计的关键组成部分。需要为研究人员和资助者提供关于试验设计这一方面的设定和报告的更好指导。该项目的目的是为研究人员和资助者制定基于共识的指导意见。
