Nonparametric Bayesian Instrumental Variable Analysis: Evaluating Heterogeneous Effects of Coronary Arterial Access Site Strategies

Percutaneous coronary interventions (PCIs) are nonsurgical procedures to open blocked blood vessels to the heart, frequently using a catheter to place a stent. The catheter can be inserted into the blood vessels using an artery in the groin or an artery in the wrist. Because clinical trials have indicated that access via the wrist may result in fewer post procedure complications, shortening the length of stay, and ultimately cost less than groin access, adoption of access via the wrist has been encouraged. However, patients treated in usual care are likely to differ from those participating in clinical trials, and there is reason to believe that the effectiveness of wrist access may differ between males and females. Moreover, the choice of artery access strategy is likely to be influenced by patient or physician unmeasured factors. To study the effectiveness of the two artery access site strategies on hospitalization charges, we use data from a state-mandated clinical registry including 7963 patients undergoing PCI. A hierarchical Bayesian likelihood-based instrumental variable analysis under a latent index modeling framework is introduced to jointly model outcomes and treatment status. Our approach accounts for unobserved heterogeneity via a latent factor structure, and permits nonparametric error distributions with Dirichlet process mixture models. Our results demonstrate that artery access in the wrist reduces hospitalization charges compared to access in the groin, with a higher mean reduction for male patients.
Supplementary materials for this article are available online.

经皮冠状动脉介入治疗（Percutaneous coronary interventions, PCIs）是一类用于疏通心脏阻塞血管的非手术操作，通常借助导管置入支架。导管可经腹股沟动脉或腕部动脉插入血管。既往临床试验表明，相较于经腹股沟动脉入路，腕部动脉入路可降低术后并发症发生率、缩短住院时长，且总体医疗成本更低，因此腕部入路的临床应用得到推广。
然而，常规诊疗中的患者与临床试验受试者可能存在异质性，且有证据表明腕部入路的疗效可能存在性别差异。此外，动脉入路策略的选择还可能受到患者或医师层面未观测混杂因素的影响。
为探究两种动脉入路策略对住院费用的影响，本研究使用了某州强制要求的临床登记数据集，该数据集涵盖7963名接受经皮冠状动脉介入治疗的患者。本文提出了一种基于隐变量索引建模框架的、基于似然的分层贝叶斯工具变量分析方法，用于联合建模治疗结局与治疗状态。该方法通过隐因子结构处理未观测异质性，并借助狄利克雷过程混合模型（Dirichlet process mixture models）实现非参数化误差分布建模。研究结果显示，相较于腹股沟动脉入路，腕部动脉入路可降低患者住院费用，且男性患者的费用平均降幅更高。
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