Leon Andrew C, Demirtas Hakan, Li Chunshan, Hedeker Donald
Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA.
Pharm Stat. 2013 Sep-Oct;12(5):268-74. doi: 10.1002/pst.1580. Epub 2013 Jun 25.
In a cluster randomized controlled trial (RCT), the number of randomized units is typically considerably smaller than in trials where the unit of randomization is the patient. If the number of randomized clusters is small, there is a reasonable chance of baseline imbalance between the experimental and control groups. This imbalance threatens the validity of inferences regarding post-treatment intervention effects unless an appropriate statistical adjustment is used. Here, we consider application of the propensity score adjustment for cluster RCTs. For the purpose of illustration, we apply the propensity adjustment to a cluster RCT that evaluated an intervention to reduce suicidal ideation and depression. This approach to adjusting imbalance had considerable bearing on the interpretation of results. A simulation study demonstrates that the propensity adjustment reduced well over 90% of the bias seen in unadjusted models for the specifications examined.
在一项整群随机对照试验（RCT）中，随机分组的单位数量通常比以患者作为随机分组单位的试验中的数量要少得多。如果随机分组的整群数量较少，那么实验组和对照组之间存在基线失衡的合理可能性。除非使用适当的统计调整，否则这种失衡会威胁到关于治疗后干预效果推断的有效性。在此，我们考虑将倾向得分调整应用于整群RCT。为了说明目的，我们将倾向得分调整应用于一项评估减少自杀意念和抑郁的干预措施的整群RCT。这种调整失衡的方法对结果的解释有相当大的影响。一项模拟研究表明，对于所研究的规格，倾向得分调整减少了未调整模型中超过90%的偏差。
