Cook Jonathan A, Hislop Jenni, Altman Douglas G, Fayers Peter, Briggs Andrew H, Ramsay Craig R, Norrie John D, Harvey Ian M, Buckley Brian, Fergusson Dean, Ford Ian, Vale Luke D
Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK.
Health Services Research Unit, University of Aberdeen, Health Sciences Building, Foresthill, Aberdeen, AB25 2ZD, UK.
Trials. 2015 Jan 15;16:12. doi: 10.1186/s13063-014-0526-8.
Central to the design of a randomised controlled trial is the calculation of the number of participants needed. This is typically achieved by specifying a target difference and calculating the corresponding sample size, which provides reassurance that the trial will have the required statistical power (at the planned statistical significance level) to identify whether a difference of a particular magnitude exists. Beyond pure statistical or scientific concerns, it is ethically imperative that an appropriate number of participants should be recruited. Despite the critical role of the target difference for the primary outcome in the design of randomised controlled trials, its determination has received surprisingly little attention. This article provides guidance on the specification of the target difference for the primary outcome in a sample size calculation for a two parallel group randomised controlled trial with a superiority question.
This work was part of the DELTA (Difference ELicitation in TriAls) project. Draft guidance was developed by the project steering and advisory groups utilising the results of the systematic review and surveys. Findings were circulated and presented to members of the combined group at a face-to-face meeting, along with a proposed outline of the guidance document structure, containing recommendations and reporting items for a trial protocol and report. The guidance and was subsequently drafted and circulated for further comment before finalisation.
Guidance on specification of a target difference in the primary outcome for a two group parallel randomised controlled trial was produced. Additionally, a list of reporting items for protocols and trial reports was generated.
Specification of the target difference for the primary outcome is a key component of a randomized controlled trial sample size calculation. There is a need for better justification of the target difference and reporting of its specification.
随机对照试验设计的核心是计算所需的参与者数量。这通常通过指定目标差异并计算相应的样本量来实现，这能确保试验具有所需的统计效力（在计划的统计显著性水平下），以确定是否存在特定大小的差异。除了纯粹的统计或科学考量外，从伦理角度出发，招募适当数量的参与者也至关重要。尽管目标差异对随机对照试验设计中的主要结局起着关键作用，但其确定却出人意料地很少受到关注。本文为有优效性问题的两组平行随机对照试验样本量计算中主要结局目标差异的设定提供指导。
这项工作是DELTA（试验中的差异引出）项目的一部分。项目指导和咨询小组利用系统评价和调查结果制定了初步指导意见。研究结果进行了传阅，并在一次面对面会议上向联合小组的成员进行了汇报，同时还提出了指导文件结构的大纲，其中包含试验方案和报告的建议及报告项目。该指导意见随后进行了起草和传阅，以供进一步评论，然后定稿。
制定了两组平行随机对照试验主要结局目标差异设定的指导意见。此外，还生成了方案和试验报告的报告项目清单。
主要结局目标差异的设定是随机对照试验样本量计算的关键组成部分。需要对目标差异进行更好的论证，并报告其设定情况。
