Greenhouse J B, Meyer M M
Department of Statistics, Carnegie Mellon University, Pittsburgh, PA 15213.
Psychopharmacol Bull. 1991;27(3):225-9.
In this article we demonstrate that even in randomized controlled clinical trials, unobserved confounding variables can bias the outcome of a study. For the case of a two-phase maintenance therapy trial where patients who respond to treatment during the acute phase are then randomized to a maintenance therapy, we show explicitly the role that confounding may play in biasing the interpretation of the results of such a trial. We suggest an alternative design to deal with the problem of a selection effect for treatment responders in the acute phase of the trial by randomizing patients at the outset of the study to both an acute and maintenance therapy.
在本文中，我们证明，即使在随机对照临床试验中，未观察到的混杂变量也可能使研究结果产生偏差。对于两阶段维持治疗试验的情况，即急性期对治疗有反应的患者随后被随机分配到维持治疗组，我们明确展示了混杂因素在使此类试验结果的解释产生偏差方面可能发挥的作用。我们提出了一种替代设计，通过在研究开始时将患者随机分配到急性治疗和维持治疗组，来解决试验急性期治疗反应者的选择效应问题。
