The Effects of Competition on Health Insurance Generosity in Medicare Advantage

描述(由申请人提供)：该项目测试健康保险市场竞争的变化如何影响费用分担和覆盖福利的慷慨程度。过去的经验研究表明，减少保险公司的竞争可以增加保险保费。然而，利润最大化的保险公司也选择其他计划特征，如共同支付、免赔额和承保福利。当竞争减少时，保险公司也可以减少这些福利的慷慨程度，这可能是最好的。了解竞争对保险慷慨程度的影响对于当前的卫生政策至关重要，因为最近的保险市场改革，如《平价医疗法案》，依赖竞争作为改善机会和福利质量的关键机制。尽管有政策含义，但关于竞争和利益之间关系的文献有限且相互矛盾。为了测试保险公司竞争对费用分担和覆盖收益的慷慨程度的影响，该项目使用了一种准实验设计，利用医疗保险优势(MA)市场竞争的差异。这种差异是由医疗保险政策的变化引起的，该政策要求私人收费服务(PFFS)计划形成提供商网络。为了应对这一变化，许多保险公司取消了计划。这些取消导致提供这些保险计划的市场的竞争发生变化，减少了保险公司的市场份额，或导致保险公司退出市场。为了确定因果关系， 本研究的重点是19家保险公司在全国范围内取消所有保费合同所引起的竞争变化。这些取消导致的竞争变化似乎与令人困惑的变量无关，因为这些保险公司取消了所有的Pff计划，而不是有选择地退出利润较低的市场。目标1将使用改进的差异差异(DIND)框架和受益人预期自付成本来测试竞争与总体计划慷慨之间的关系，受益人预期自付成本是代表联邦医疗保险计算的健康计划慷慨程度的汇总衡量标准。经修订的DIND框架通过比较取消前后市场内以及取消程度不同的市场之间的利益，确定了竞争的影响。县和年固定效应有助于控制未观察到的福利变化。为了进一步测试变化是否与竞争的变化有关，可以评估市场竞争的基线水平和计划替代模式的差异的不同影响。AIM 2使用相同的框架来测试竞争对特定服务的免赔额和共付金的影响。AIM 3将测试这些影响是否通过被取消计划的投保人的健康风险来调节；例如，如果保险公司在投保人病情较重的市场运营，他们可能会进一步降低福利，以阻止病情较重的受益人投保。构建计划份额的数据来自汇总的、可公开获得的联邦医疗保险登记数据；有关福利的数据来自自付成本数据库和联邦医疗保险选项比较。有关计划级别健康风险得分的数据来自公开可用的计划支付数据。

DESCRIPTION (provided by applicant): This project tests how changes in health insurance market competition affect the generosity of cost-sharing and covered benefits. Past empirical research suggests that reducing insurer competition can increase plan premiums. However, profit-maximizing insurers also choose other plan characteristics, such as copays, deductibles, and covered benefits. When competition decreases, it may be optimal for insurers to reduce the generosity of these benefits as well. Understanding the effect of competition on insurance generosity is crucial for current health policy, as recent insurance market reforms such as the Affordable Care Act rely on competition as the key mechanism for improving access and benefit quality. Despite the policy implications, the literature on the relationship between competition and benefits is limited and conflicting. To test for effects of insurer competition on the generosity of cost-sharing and covered benefits, this project uses a quasi-experimental design that leverages variation in competition in the Medicare Advantage (MA) market. This variation was caused by a change in Medicare policy that required private-fee-for-service (PFFS) plans to form provider networks. In response to this change, many insurers cancelled plans. These cancellations caused variation in competition in the markets where these plans were offered, by reducing insurers' market share or causing insurers to exit the market. To identify causal effects, this study focuses on changes in competition caused by 19 insurers who cancelled all PFFS contracts nationally. Changes in competition caused by these cancellations are plausibly unrelated to confounding variables, as these insurers cancelled all PFFS plans rather than selectively exiting less profitable markets. Aim 1 will test for a relationship between competitio and overall plan generosity, using a modified difference-in-difference (DinD) framework and beneficiary expected out-of-pocket costs, a summary measure of health plan generosity calculated on behalf of Medicare. The modified DinD framework identifies the effects of competition by comparing benefits within markets before and after cancellation and across markets with different levels of cancellation. County- and year-fixed effects help control for unobserved variation in benefits. To further test whether changes are related to changes in competition, differing effects by baseline levels of market competition and differences in plan substitution patterns can be assessed. Aim 2 uses the same framework to test for effects of competition on deductibles and copays for specific services. Aim 3 will test whether these effects are mediated by the health risk of enrollees in cancelled plans; for instance, if insurers are operating in markets with sicker enrollees, they may further degrade benefits to deter sicker beneficiaries from enrolling. Data to construct plan shares comes from aggregate, publicly-available Medicare enrollment data; data on benefits comes from the out-of-pocket cost database and Medicare Options Compare. Data on plan-level health risk scores comes from publicly-available plan payment data.