The use of random effects models to allow for clustering in individually randomized trials
The use of random effects models to allow for clustering in individually randomized trials
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DOI：
10.1191/1740774505cn082oa
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发表时间：
2005-01-01
期刊：
影响因子：
2.7
通讯作者：
Thompson, SG
中科院分区：
文献类型：
--
作者：
Lee, KJ;Thompson, SG
背景我们描述了在个体随机试验中可能出现的不同形式的聚类，其中观察到的不同个体的结果不能被认为是独立的。我们提出了随机效应模型，以允许这样的集群，在一系列的背景和试验设计，并探讨其效果的估计和解释的治疗effect.Methods我们提出的模型，两个单独的随机试验与集群的潜力，远程会诊在医院转诊中的试验（主要结果是提供进一步的医院预约）和由物理治疗师提供的用于腰痛的运动疗法的试验（结果是背痛评分）。该方法的扩展包括使用聚类水平特征解释聚类之间异质性的可能性，以及由于不依从性导致的聚类效应的潜在稀释。（1.52，95% CI 1.27至1.82），但考虑到医院顾问的聚类时，较小且不显著（1.36，95% CI 0.85至2.13）。顾问之间估计治疗效果的95%范围为0.21至8.76。顾问的专业只能部分解释这种差异。在背部疼痛试验中，虽然有一个整体的好处运动（变化- 0.51点的背部疼痛评分）和集群的证据很少，估计不同的物理治疗师的治疗效果范围从-1.26到+0.26points.Conclusions集群是一个重要的问题，在许多单独的随机试验。忽略它可能会导致低估不确定性和过于极端的P值。即使在集群之间几乎没有明显的异质性，它仍然可以对治疗效果的估计和解释产生很大的影响。
Background We describe different forms of clustering that may occur in individually randomized trials, where the observed outcomes for different individuals cannot be regarded as independent. We propose random effects models to allow for such clustering, across a range of contexts and trial designs, and investigate their effect on estimation and interpretation of the treatment effect.Methods We apply our proposed models to two individually randomized trials with potential for clustering, a trial of teleconsultation in hospital referral (the main outcome being offer of a further hospital appointment) and a trial of exercise therapy delivered by physiotherapists for low back pain (the outcome being a back pain score). Extensions to the methods include the possibility of explaining heterogeneity between clusters using cluster level characteristics and the potential dilution of cluster effects due to noncompliance.Results In the teleconsultation trial, the odds ratio was significant (1.52, 95% Cl 1.27 to 1.82) when clustering was ignored, but smaller and nonsignificant (1.36, 95% Cl 0.85 to 2.13) when clustering by hospital consultant was taken into account. The 95% range of estimated treatment effects across consultants was from 0.21 to 8.76. This variability was only partially explained by the specialty of the consultant. In the back pain trial, although there was an overall benefit of exercise (change of - 0.51 points on the back pain score) and little evidence of clustering, the estimated treatment effects for different physiotherapists ranged from - 1.26 to +0.26 points.Conclusions Clustering is an important issue in many individually randomized trials. Ignoring it can lead to underestimates of the uncertainty and too extreme P-values. Even when there is little apparent heterogeneity across clusters, it can still have a large impact on the estimation and interpretation of the treatment effect.