Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Oxford OX3 7LD, UK
Medical Statistics Group, ScHARR, University of Sheffield, Sheffield, UK.
BMJ. 2018 Nov 5;363:k3750. doi: 10.1136/bmj.k3750.
Randomised controlled trials are considered to be the best method to assess comparative clinical efficacy and effectiveness, and can be a key source of data for estimating cost effectiveness. Central to the design of a randomised controlled trial is an a priori sample size calculation, which ensures that the study has a high probability of achieving its prespecified main objective. Beyond pure statistical or scientific concerns, it is ethically imperative that an appropriate number of study participants be recruited, to avoid imposing the burdens of a clinical trial on more patients than necessary. The scientific concern is satisfied and the ethical imperative is further addressed by the specification of a target difference between treatments that is considered realistic or important by one or more key stakeholder groups. The sample size calculation ensures that the trial will have the required statistical power to identify whether a difference of a particular magnitude exists. In this article, the key messages from the DELTA guidance on determining the target difference and sample size calculation for a randomised controlled trial are presented. Recommendations for the subsequent reporting of the sample size calculation are also provided.
随机对照试验被认为是评估临床疗效和有效性的最佳方法，也是估计成本效益的关键数据来源。随机对照试验设计的核心是事先进行样本量计算，以确保研究有很大的概率实现其预先规定的主要目标。除了纯粹的统计或科学问题外，从伦理角度来看，必须招募适当数量的研究参与者，以避免将临床试验的负担强加给不必要的更多患者。通过规定一个或多个关键利益相关者群体认为现实或重要的治疗方法之间的目标差异，可以满足科学关注并进一步解决伦理要求。样本量计算可确保试验具有所需的统计效力来确定是否存在特定大小的差异。本文介绍了 DELTA 指南中关于确定随机对照试验目标差异和样本量计算的关键信息。还提供了对随后报告样本量计算的建议。
