RAND Corporation, 1200 S Hayes St, Arlington, VA 22202. Email:
Am J Manag Care. 2020 Nov 1;26(11):e355-e361. doi: 10.37765/ajmc.2020.88530.
The use of generics in Medicare Part D generates cost savings for plan sponsors, beneficiaries, and the federal government. However, there is considerable variation in generic use across plans, even within a therapeutic class. Our objective is to understand the extent of variation in generic use in Part D and to understand factors associated with generic use.
We used an observational study design using Medicare Part D claims from 2006 to 2016.
We used descriptive statistics and regression analysis to examine the variation in generic and brand use across plans and the extent to which patient, plan, and area characteristics are associated with the choice of medication within a therapeutic class.
Although generic use has increased markedly over time in Part D, substantial variation across plans persists in a number of common therapeutic classes. Beneficiary characteristics such as gender and health status are associated with higher/lower generic use, as are plan characteristics such as plan type (stand-alone prescription drug plan or Medicare Advantage), premium, and parent company.
Because we cannot study the impact of brand-name drug rebates on generic use, we can study the variation in generic use across Part D plans as an indirect way to assess pharmacy benefit manager and plan incentives. We find circumstantial evidence that, in certain classes, rebates may play a role in influencing brand over generic use, although the exact relationship is unknowable given the proprietary nature of rebates.
医疗保险计划 D 中使用仿制药可为计划赞助商、受益人和联邦政府节省成本。然而，即使在同一治疗类别内，不同计划之间的仿制药使用情况也存在很大差异。我们的目的是了解医疗保险计划 D 中仿制药使用情况的差异程度，并了解与仿制药使用相关的因素。
我们使用了一项观察性研究设计，使用了 2006 年至 2016 年的医疗保险计划 D 索赔数据。
我们使用描述性统计和回归分析来检查计划之间在仿制药和品牌药使用方面的差异，以及患者、计划和地区特征与治疗类别内药物选择之间的关联程度。
尽管在医疗保险计划 D 中，仿制药的使用在过去几年中显著增加，但在一些常见的治疗类别中，不同计划之间仍然存在很大差异。受益人的特征，如性别和健康状况，与更高/更低的仿制药使用有关，而计划的特征，如计划类型（独立处方药计划或医疗保险优势计划）、保费和母公司，也与仿制药使用有关。
由于我们无法研究品牌药物回扣对仿制药使用的影响，因此我们可以研究医疗保险计划 D 中仿制药使用情况的差异，这是评估药房福利经理和计划激励措施的一种间接方法。我们发现了一些间接证据，表明在某些类别中，回扣可能在影响品牌药替代仿制药方面发挥了作用，尽管由于回扣的性质是保密的，因此无法确定确切的关系。
