Impact of mis-specification of the treatment model on estimates from a marginal structural model
Impact of mis-specification of the treatment model on estimates from a marginal structural model
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DOI：
10.1002/sim.3200
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发表时间：
2008-08-15
影响因子：
2
通讯作者：
Platt, Robert W.
中科院分区：
文献类型：
--
作者：
Lefebvre, Genevieve;Delaney, Joseph A. C.;Platt, Robert W.
边际结构模型 (MSM) 的治疗加权逆概率 (IPTW) 估计需要指定一个描述治疗分配和混杂因素之间条件关系的干扰模型。然而，关于在实践中构建这些治疗模型的最佳策略的信息仍然有限。我们开发了一系列模拟来系统地确定在此类模型中包含不同类型的候选变量的效果。我们探索了 IPTW 估计器在复杂性不断增加的几种场景中的性能，包括旨在模拟大型药物流行病学研究中常见的复杂性的场景。我们的结果表明，在治疗模型中包含治疗的纯粹预测因子（即非混杂因素）可能会导致估计器出现偏差且高度可变，特别是在小样本的情况下。基于MSM的IPTW估计器的偏差和均方误差随着问题复杂性的增加而增加。通过增加样本量或仅使用与结果相关的变量来开发治疗模型，可以提高估计器的性能。基于真实治疗概率模型的治疗效果估计是渐近无偏的。我们建议在开发基于 IPTW 的 MSM 时，在治疗模型中仅包括纯粹的风险因素和混杂因素。版权所有 (C) 2008 约翰·威利父子有限公司
Inverse probability of treatment weighted (IPTW) estimation for marginal structural models (MSMs) requires the specification of a nuisance model describing the conditional relationship between treatment allocation and confounders. However, there is still limited information on the best strategy for building these treatment models in practice. We developed a series of simulations to systematically determine the effect of including different types of candidate variables in such models. We explored the performance of IPTW estimators across several scenarios of increasing complexity, including one designed to mimic the complexity typically seen in large pharmacoepidemiologic studies.Our results show that including pure predictors of treatment (i.e. not confounders) in treatment models can lead to estimators that are biased and highly variable, particularly in the context of small samples. The bias and mean-squared error of the MSM-based IPTW estimator increase as the complexity of the problem increases. The performance of the estimator is improved by either increasing the sample size or using only variables related to the outcome to develop the treatment model. Estimates of treatment effect based on the true model for the probability of treatment are asymptotically unbiased.We recommend including only pure risk factors and confounders in the treatment model when developing an IPTW-based MSM. Copyright (C) 2008 John Wiley & Sons, Ltd.