从历史上看，先验功效和样本量计算在成本效益分析中并不常规地进行，部分原因是缺乏已发表的成本和效果相关性和方差数据，这些数据对于功效和样本量计算至关重要。重要的是，成本和效果之间的实证相关性在临床文献中的价值估算方面尚未得到研究。因此，嵌入在随机对照试验(RCTs)中的成本效益研究是否能够准确检测到价值估算的变化尚未明确。然而，最近的指南(如ISPOR的指南)和资助机构建议在临床试验中嵌入的成本效益分析中考虑样本量和功效计算。我们考察了由加拿大癌症试验组(Canadian Cancer Trials Group)进行的所有嵌入成本效益分析的RCTs。基于原始试验数据，我们得到了效果和成本的方差和相关性。利用递增净效益法来计算成本效益分析的功效，并探索替代相关性和愿意支付值。我们确定了四个试验进行了包括。我们观察到，假设成本和效果之间的相关系数为零，在样本量估计中得到了保守的估计。在两个试验中，在愿意支付$100,000的情况下，成本效益分析无法准确检测到价值估算的变化。根据我们的观察，我们提出了六个未来经济评估的考虑因素，并提供一个在线程序，帮助分析师在未来的临床试验中进行先验样本量和功效计算。成本和效果之间的相关性对于所研究的成本效益分析中的价值估算的功效和方差有着潜在的重要影响。因此，这六个考虑因素和在线程序可能有助于在未来的临床试验中进行先验样本量计算的嵌入成本效益分析。© 2023. BioMed Central Ltd., part of Springer Nature.

Historically, a priori power and sample size calculations have not been routinely performed cost-effectiveness analyses (CEA), partly because the absence of published cost and effectiveness correlation and variance data, which are essential for power and sample size calculations. Importantly, the empirical correlation between cost and effectiveness has not been examined with respect to the estimation of value-for-money in clinical literature. Therefore, it is not well established if cost-effectiveness studies embedded within randomized-controlled-trials (RCTs) are under- or over-powered to detect changes in value-for-money. However, recently guidelines (such as those from ISPOR) and funding agencies have suggested sample size and power calculations should be considered in CEAs embedded in clinical trials.We examined all RCTs conducted by the Canadian Cancer Trials Group with an embedded cost-effectiveness analysis. Variance and correlation of effectiveness and costs were derived from original-trial data. The incremental net benefit method was used to calculate the power of the cost-effectiveness analysis, with exploration of alternative correlation and willingness-to-pay values.We identified four trials for inclusion. We observed that a hypothetical scenario of correlation coefficient of zero between cost and effectiveness led to a conservative estimate of sample size. The cost-effectiveness analysis was under-powered to detect changes in value-for-money in two trials, at willingness-to-pay of $100,000. Based on our observations, we present six considerations for future economic evaluations, and an online program to help analysts include a priori sample size and power calculations in future clinical trials.The correlation between cost and effectiveness had a potentially meaningful impact on the power and variance of value-for-money estimates in the examined cost-effectiveness analyses. Therefore, the six considerations and online program, may facilitate a priori power calculations in embedded cost-effectiveness analyses in future clinical trials.© 2023. BioMed Central Ltd., part of Springer Nature.