Institute of Clinical Trials, West China Hospital, Sichuan University, Sichuan, People's Republic of China.
Stat Med. 2012 Mar 30;31(7):681-97. doi: 10.1002/sim.4168. Epub 2011 Feb 24.
The propensity score method is widely used in clinical studies to estimate the effect of a treatment with two levels on patient's outcomes. However, due to the complexity of many diseases, an effective treatment often involves multiple components. For example, in the practice of Traditional Chinese Medicine (TCM), an effective treatment may include multiple components, e.g. Chinese herbs, acupuncture, and massage therapy. In clinical trials involving TCM, patients could be randomly assigned to either the treatment or control group, but they or their doctors may make different choices about which treatment component to use. As a result, treatment components are not randomly assigned. Rosenbaum and Rubin proposed the propensity score method for binary treatments, and Imbens extended their work to multiple treatments. These authors defined the generalized propensity score as the conditional probability of receiving a particular level of the treatment given the pre-treatment variables. In the present work, we adopted this approach and developed a statistical methodology based on the generalized propensity score in order to estimate treatment effects in the case of multiple treatments. Two methods were discussed and compared: propensity score regression adjustment and propensity score weighting. We used these methods to assess the relative effectiveness of individual treatments in the multiple-treatment IMPACT clinical trial. The results reveal that both methods perform well when the sample size is moderate or large.
倾向评分法被广泛应用于临床研究中，以估计两种水平的治疗方法对患者结局的影响。然而，由于许多疾病的复杂性，有效的治疗往往涉及多个组成部分。例如，在中医（TCM）实践中，有效的治疗可能包括多种成分，如中草药、针灸和按摩疗法。在涉及 TCM 的临床试验中，患者可以被随机分配到治疗组或对照组，但他们或他们的医生可能会对使用哪种治疗成分做出不同的选择。因此，治疗成分不是随机分配的。Rosenbaum 和 Rubin 提出了用于二分类治疗的倾向评分法，Imbens 将他们的工作扩展到了多种治疗方法。这些作者将广义倾向评分定义为在给定预处理变量的情况下接受特定治疗水平的条件概率。在本工作中，我们采用了这种方法，并基于广义倾向评分开发了一种统计方法，以在多种治疗情况下估计治疗效果。讨论并比较了两种方法：倾向评分回归调整和倾向评分加权。我们使用这些方法评估了在多治疗 IMPACT 临床试验中单个治疗的相对有效性。结果表明，当样本量适中或较大时，这两种方法都表现良好。
