Abstract：
The sample size calculation is an important step in designing randomised controlled trials. For a trial comparing a control and an intervention group, where the outcome is binary, the sample size calculation requires choosing values for the anticipated event rates in both the control and intervention groups (the effect size), and the error rates. The Difference ELicitation in TriAls guidance recommends that the effect size should be both realistic, and clinically important to stakeholder groups. Overestimating the effect size leads to sample sizes that are too small to reliably detect the true population effect size, which in turn results in low achieved power. In this study, we use the Delphi approach to gain consensus on what the minimum clinically important effect size is for Balanced-2, a randomised controlled trial comparing processed electroencephalogram-guided \'light\' to \'deep\' general anaesthesia on the incidence of postoperative delirium in older adults undergoing major surgery.
Delphi rounds were conducted using electronic surveys. Surveys were administered to two stakeholder groups: specialist anaesthetists from a general adult department in Auckland City Hospital, New Zealand (Group 1), and specialist anaesthetists with expertise in clinical research, identified from the Australian and New Zealand College of Anaesthetist\'s Clinical Trials Network (Group 2). A total of 187 anaesthetists were invited to participate (81 from Group 1 and 106 from Group 2). Results from each Delphi round were summarised and presented in subsequent rounds until consensus was reached (>70% agreement).
The overall response rate for the first Delphi survey was 47% (88/187). The median minimum clinically important effect size was 5.0% (interquartile range: 5.0-10.0) for both stakeholder groups. The overall response rate for the second Delphi survey was 51% (95/187). Consensus was reached after the second round, as 74% of respondents in Group 1 and 82% of respondents in Group 2 agreed with the median effect size. The combined minimum clinically important effect size across both groups was 5.0% (interquartile range: 3.0-6.5).
This study demonstrates that surveying stakeholder groups using a Delphi process is a simple way of defining a minimum clinically important effect size, which aids the sample size calculation and determines whether a randomised study is feasible.
Delphi rounds were conducted using electronic surveys. Surveys were administered to two stakeholder groups: specialist anaesthetists from a general adult department in Auckland City Hospital, New Zealand (Group 1), and specialist anaesthetists with expertise in clinical research, identified from the Australian and New Zealand College of Anaesthetist\'s Clinical Trials Network (Group 2). A total of 187 anaesthetists were invited to participate (81 from Group 1 and 106 from Group 2). Results from each Delphi round were summarised and presented in subsequent rounds until consensus was reached (>70% agreement).
The overall response rate for the first Delphi survey was 47% (88/187). The median minimum clinically important effect size was 5.0% (interquartile range: 5.0-10.0) for both stakeholder groups. The overall response rate for the second Delphi survey was 51% (95/187). Consensus was reached after the second round, as 74% of respondents in Group 1 and 82% of respondents in Group 2 agreed with the median effect size. The combined minimum clinically important effect size across both groups was 5.0% (interquartile range: 3.0-6.5).
This study demonstrates that surveying stakeholder groups using a Delphi process is a simple way of defining a minimum clinically important effect size, which aids the sample size calculation and determines whether a randomised study is feasible.
摘要：
■样本量计算是设计随机对照试验的重要步骤。对于比较对照组和干预组的试验，结果是二进制的，样本量计算需要选择对照组和干预组的预期事件发生率的值(效应大小)，和错误率。TriAls指南中的差异启发建议效果大小应该既现实，以及对利益相关者群体的临床重要性。高估效应大小会导致样本量太小，无法可靠地检测真实的群体效应大小，这又导致实现的功率低。在这项研究中,我们使用Delphi方法就Balanced-2的最小临床重要效应大小达成共识，Balanced-2是一项随机对照试验，比较了脑电图引导下的“轻度”至“深度”全身麻醉对接受大手术的老年人术后谵妄发生率的影响。
■使用电子调查进行了德尔菲轮。对两个利益相关者进行了调查：来自奥克兰市医院普通成人部门的专业麻醉师，新西兰（第1组），和具有临床研究专长的专业麻醉师，来自澳大利亚和新西兰麻醉师学院的临床试验网络（第2组）。总共邀请了187名麻醉师参加（第1组81名，第2组106名）。总结来自每个Delphi轮的结果并在随后的轮中呈现,直到达成共识(>70%一致)。
■第一次Delphi调查的总体响应率为47％（88/187）。两个利益相关者组的中位数最小临床重要效应大小为5.0％（四分位距：5.0-10.0）。第二次Delphi调查的总应答率为51%(95/187)。第二轮后达成共识,因为第1组74%的受访者和第2组82%的受访者同意中值效应大小.两组的联合最小临床重要效应大小为5.0％（四分位距：3.0-6.5）。
■这项研究表明，使用Delphi过程调查利益相关者群体是定义最小临床重要效应大小的简单方法，这有助于样本量计算，并确定随机研究是否可行。
■使用电子调查进行了德尔菲轮。对两个利益相关者进行了调查：来自奥克兰市医院普通成人部门的专业麻醉师，新西兰（第1组），和具有临床研究专长的专业麻醉师，来自澳大利亚和新西兰麻醉师学院的临床试验网络（第2组）。总共邀请了187名麻醉师参加（第1组81名，第2组106名）。总结来自每个Delphi轮的结果并在随后的轮中呈现,直到达成共识(>70%一致)。
■第一次Delphi调查的总体响应率为47％（88/187）。两个利益相关者组的中位数最小临床重要效应大小为5.0％（四分位距：5.0-10.0）。第二次Delphi调查的总应答率为51%(95/187)。第二轮后达成共识,因为第1组74%的受访者和第2组82%的受访者同意中值效应大小.两组的联合最小临床重要效应大小为5.0％（四分位距：3.0-6.5）。
■这项研究表明，使用Delphi过程调查利益相关者群体是定义最小临床重要效应大小的简单方法，这有助于样本量计算，并确定随机研究是否可行。
