MRC Clinical Trials Unit at UCL, Institute of Clinical Trials and Methodology, UCL, London, UK.
Department of Biostatistics, Vanderbilt University Medical Center, Nashville, USA.
Stat Methods Med Res. 2024 Jul;33(7):1211-1232. doi: 10.1177/09622802241254197. Epub 2024 May 23.
Estimands can help clarify the interpretation of treatment effects and ensure that estimators are aligned with the study's objectives. Cluster-randomised trials require additional attributes to be defined within the estimand compared to individually randomised trials, including whether treatment effects are or , and whether they are or . In this paper, we provide formal definitions of estimands encompassing both these attributes using potential outcomes notation and describe differences between them. We then provide an overview of estimators for each estimand, describe their assumptions, and show consistency (i.e. asymptotically unbiased estimation) for a series of analyses based on cluster-level summaries. Then, through a re-analysis of a published cluster-randomised trial, we demonstrate that the choice of both estimand and estimator can affect interpretation. For instance, the estimated odds ratio ranged from 1.38 ( = 0.17) to 1.83 ( = 0.03) depending on the target estimand, and for some estimands, the choice of estimator affected the conclusions by leading to smaller treatment effect estimates. We conclude that careful specification of the estimand, along with an appropriate choice of estimator, is essential to ensuring that cluster-randomised trials address the right question.
效标可以帮助澄清治疗效果的解释，并确保估计量与研究目标一致。与个体随机试验相比，群组随机试验需要在效标中定义额外的属性，包括治疗效果是固定还是随机，以及它们是个体还是群组效应。在本文中，我们使用潜在结果表示法为包含这两个属性的效标提供了正式定义，并描述了它们之间的差异。然后，我们为每个效标提供了估计量的概述，描述了它们的假设，并展示了基于群组水平汇总的一系列分析的一致性（即渐近无偏估计）。然后，通过对已发表的群组随机试验的重新分析，我们表明效标和估计量的选择都会影响解释。例如，根据目标效标，估计的比值比范围为 1.38（ = 0.17）至 1.83（ = 0.03），对于某些效标，估计量的选择会通过导致较小的治疗效果估计值来影响结论。我们得出结论，仔细指定效标以及适当选择估计量对于确保群组随机试验解决正确的问题至关重要。
