Accountable care organization (ACO) legislation was designed to improve patient outcomes by inducing greater coordination of care and adoption of best practices. Therefore, it is of interest to assess whether greater uniformity occurs among practices comprising an ACO post ACO formation. We develop a mixed-effect model with a difference-in-difference design to evaluate the effect of a patient receiving care from an ACO on patient outcomes and adapt this model to examine whether an ACO is associated with increased uniformity across its constituent practices. The task is complicated by the organizations within an ACO forming an additional layer in the multilevel model, due to medical practices and hospitals that form an ACOs being nested within the ACO, making the number of levels of the model variable and the dimension of the parameter space time-varying. We develop the model and a procedure for testing the hypothesis that ACO formation was associated with increased uniformity among its constituent practices. We apply our procedure to a cohort of medicare beneficiaries followed over 2009-2014. Although there is extensive heterogeneity of becoming an ACOs across practices, we find that the formation of an ACO appears to be associated with greater uniformity of patient outcomes among its constituent practices.

中文翻译：

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使用具有异质维度参数空间的混合效应模型来评估责任护理组织是否与组成实践的更大一致性相关联

责任医疗组织 (ACO) 立法旨在通过加强医疗协调和采用最佳实践来改善患者的治疗效果。因此，有必要评估在 ACO 形成后组成 ACO 的实践之间是否出现更大的一致性。我们开发了一个采用差分设计的混合效应模型，以评估接受 ACO 护理的患者对患者结果的影响，并调整该模型以检查 ACO 是否与其组成实践的一致性增加相关。由于形成 ACO 的医疗实践和医院嵌套在 ACO 中，ACO 内的组织在多级模型中形成了一个附加层，因此任务变得复杂，使模型变量的层数和参数空间的维数随时间变化。我们开发了模型和程序来检验 ACO 形成与其组成实践之间的一致性增加相关的假设。我们将我们的程序应用于 2009-2014 年随访的一组医疗保险受益人。尽管在不同实践中成为 ACO 存在广泛的异质性，但我们发现 ACO 的形成似乎与其组成实践中患者结果的更大一致性有关。