Design effect in multicenter studies: gain or loss of power?
Design effect in multicenter studies: gain or loss of power?
复制标题
DOI：
10.1186/1471-2288-9-39
复制
发表时间：
2009-06-18
影响因子：
4
通讯作者：
Giraudeau, Bruno
中科院分区：
文献类型：
--
作者：
Vierron, Emilie;Giraudeau, Bruno
背景：在多中心试验中，属于同一中心的受试者的反应是相关的。这种聚类通常通过设计效果来评估，设计效果定义为两个方差的比率。这项工作的目的是描述和理解设计效果涉及权力增益或损失的情况。方法：我们为多中心研究开发了一个设计效果公式，旨在测试二元因素（从而定义两个组）对连续结果的影响，并探索了几种设计的设计效果（从单独分层随机试验到整群随机试验，以及其他设计，如配对设计或观察性多中心研究）。结果：设计效果取决于组内相关系数（ICC）（评估组内相关系数）来自同一中心的两个受试者数据之间的相关性），而且还取决于统计量 S，该统计量量化了中心之间组分布的异质性（从而量化了二元因素与中心之间的关联程度）以及两组之间的全局不平衡程度（受试者数量不同）。这种设计效应可能会导致功效的损失或增加，具体取决于 S 统计量是否分别高于或低于 1。结论：我们提供了适用于任何多中心研究的全局设计效果公式，并允许识别与此类研究中的功效增加或损失相关的因素（ICC 和中心之间的组比例分布）。
Background: In a multicenter trial, responses for subjects belonging to a common center are correlated. Such a clustering is usually assessed through the design effect, defined as a ratio of two variances. The aim of this work was to describe and understand situations where the design effect involves a gain or a loss of power.Methods: We developed a design effect formula for a multicenter study aimed at testing the effect of a binary factor (which thus defines two groups) on a continuous outcome, and explored this design effect for several designs (from individually stratified randomized trials to cluster randomized trials, and for other designs such as matched pair designs or observational multicenter studies).Results: The design effect depends on the intraclass correlation coefficient (ICC) (which assesses the correlation between data for two subjects from the same center) but also on a statistic S, which quantifies the heterogeneity of the group distributions among centers (thus the level of association between the binary factor and the center) and on the degree of global imbalance (the number of subjects are then different) between the two groups. This design effect may induce either a loss or a gain in power, depending on whether the S statistic is respectively higher or lower than 1.Conclusion: We provided a global design effect formula applying for any multicenter study and allowing identifying factors - the ICC and the distribution of the group proportions among centers - that are associated with a gain or a loss of power in such studies.