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arXiv 1702.07009stat.AP
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混杂因素选择对罕见事件数据倾向得分的影响--及其在出生缺陷中的应用

The Impact of Confounder Selection in Propensity Scores for Rare Events Data - with Applications to Birth Defects

Ronghui Xu, Jue Hou, Christina D. Chambers

摘要:

我们的工作是由最近的一项研究的动机婴儿出生缺陷的孕妇暴露于某种药物治疗慢性疾病。出生缺陷等结局在一般人群中是罕见事件,在未暴露组中通常转化为极少数事件。由于妊娠期药物安全性研究通常是观察性的,因此我们使用倾向得分(PS)控制了这种罕见事件背景下的混杂因素。使用我们的经验数据,我们注意到,由于暴露导致的出生缺陷的估计比值比根据所使用的具体方法而变化很大。PS常用的方法有匹配、分层、逆概率加权(IPW)和回归调整。极罕见事件设置使得匹配或分层不可行。此外,PS本身可以通过不同的方法形成,以从相对较长的潜在混杂因素列表中选择混杂因素。我们进行了模拟实验来比较不同的方法组合:IPW或回归调整,其中1)包括所有潜在的混杂因素而不进行选择,2)基于候选变量和结果之间的单变量关联进行选择,3)基于变化的选择效应(CIE)。模拟表明,IPW没有选择导致极大的方差估计的比值比,这有助于解释我们观察到的经验数据分析结果。模拟还表明,IPW与选择的基础上单变量关联的结果是首选IPW与CIE。无论使用何种选择方法,回归调整的估计比值比方差都很小。

英文摘要:

Our work was motivated by a recent study on birth defects of infants born to pregnant women exposed to a certain medication for treating chronic diseases. Outcomes such as birth defects are rare events in the general population, which often translate to very small numbers of events in the unexposed group. As drug safety studies in pregnancy are typically observational in nature, we control for confounding in this rare events setting using propensity scores (PS). Using our empirical data, we noticed that the estimated odds ratio for birth defects due to exposure varied drastically depending on the specific approach used. The commonly used approaches with PS are matching, stratification, inverse probability weighting (IPW) and regression adjustment. The extremely rare events setting renders the matching or stratification infeasible. In addition, the PS itself may be formed via different approaches to select confounders from a relatively long list of potential confounders. We carried out simulation experiments to compare different combinations of approaches: IPW or regression adjustment, with 1) including all potential confounders without selection, 2) selection based on univariate association between the candidate variable and the outcome, 3) selection based on change in effects (CIE). The simulation showed that IPW without selection leads to extremely large variances in the estimated odds ratio, which help to explain the empirical data analysis results that we had observed. The simulation also showed that IPW with selection based on univariate association with the outcome is preferred over IPW with CIE. Regression adjustment has small variances of the estimated odds ratio regardless of the selection methods used.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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