Clustering by health professional in individually randomised trials
Clustering by health professional in individually randomised trials
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DOI：
10.1136/bmj.330.7483.142
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发表时间：
2005-01-15
影响因子：
--
通讯作者：
Thompson, SG
中科院分区：
文献类型：
--
作者：
Lee, KJ;Thompson, SG
几乎所有随机化个体的试验都假设参与者的观察结果是独立的。然而，在某些情况下，这一假设的有效性值得怀疑。一个例子是当一个以上的卫生专业人员（如外科医生，护士，全科医生或治疗师）提供非药物干预的参与者。由于卫生专业人员的有效性可能各不相同，对同一专业人员治疗的参与者的观察结果可能有点相似或聚类。结果的聚类也可能不太明显（如在多中心试验中按中心聚类）或以更主导的形式出现（如在聚类随机试验中）。在每一种情况下，独立性的假设都被违反了，这意味着标准的统计方法是无效的，可能会得出误导性的结论。试验中聚类的存在增加了标准误差，减少了有效样本量，从而降低了试验的功效。我们研究了个体随机试验中潜在聚类的普遍性和重要性，并提出了一个例子，说明它可能对试验的总体结果和结论产生的影响。
Almost all trials that randomise individuals assume that the observed outcomes of participants are independent. The validity of this assumption is doubtful, however, in some situations. One example is when more than one health professional (such as surgeons, nurses, general practitioners, or therapists) delivers a non-pharmaceutical intervention to participants. Because health professionals may vary in their effectiveness, observations on participants treated by the same professional may be somewhat similar or clustered. Clustering of outcomes may also appear less obviously (such as in clustering by centre in a multicentre trial) or in a more dominant form (as in cluster randomised trials). In each of these situations the assumption of independence is violated, which means that standard statistical methods are invalid and may give misleading conclusions. The presence of clustering in a trial inflates standard errors and reduces the effective sample size, thus reducing the power of the trial. We examine the prevalence and importance of potential clustering in individually randomised trials and present an example of the effect it can have on the overall results and conclusions of a trial.