Abraham Jean Marie, Drake Coleman, McCullough Jeffrey S, Simon Kosali
Division of Health Policy and Management, University of Minnesota, Minneapolis, MN, USA.
Health Policy and Management, University of Michigan, Ann Arbor, MI, USA.
Int J Health Econ Manag. 2017 Dec;17(4):395-412. doi: 10.1007/s10754-017-9215-y. Epub 2017 Apr 26.
We investigate determinants of market entry and premiums within the context of the Affordable Care Act's Marketplaces for individual insurance. Using Bresnahan and Reiss (1991) as the conceptual framework, we study how competition and firm heterogeneity relate to premiums in 36 states using Federally Facilitated or Supported Marketplaces in 2016. Our primary data source is the Qualified Health Plan Landscape File, augmented with market characteristics from the American Community Survey and Area Health Resource File as well as insurer-level information from federal Medical Loss Ratio annual reports. We first estimate a model of insurer entry and then investigate the relationship between a market's predicted number of entrants and insurer-level premiums. Our entry model results suggest that competition is increasing with the number of insurers, most notably as the market size increases from 3 to 4 entrants. Results from the premium regression suggest that each additional entrant is associated with approximately 4% lower premiums, controlling for other factors. An alternative explanation for the relationship between entrants and premiums is that more efficient insurers (who can price lower) are the ones that enter markets with many entrants, and this is reflected in lower premiums. An exploratory analysis of insurers' non-claims costs (a proxy for insurer efficiency) reveals that average costs among entrants are rising slightly with the number of insurers in the market. This pattern does not support the hypothesis that premiums decrease with more entrants because those entrants are more efficient, suggesting instead that the results are being driven mostly by price competition.
我们在《平价医疗法案》的个人保险市场背景下，研究了市场进入和保费的决定因素。以布雷斯纳汉和赖斯（1991年）为概念框架，我们利用2016年联邦政府推动或支持的市场，研究了36个州的竞争和企业异质性与保费之间的关系。我们的主要数据来源是合格健康计划概况文件，并补充了美国社区调查和地区卫生资源文件中的市场特征以及联邦医疗损失率年度报告中的保险公司层面信息。我们首先估计了一个保险公司进入模型，然后研究了市场预测进入者数量与保险公司层面保费之间的关系。我们的进入模型结果表明，竞争随着保险公司数量的增加而加剧，最显著的是当市场规模从3个进入者增加到4个进入者时。保费回归结果表明，在控制其他因素的情况下，每增加一个进入者，保费大约会降低4%。进入者与保费之间关系的另一种解释是，效率更高（能够定价更低）的保险公司是那些进入有许多进入者的市场的公司，这反映在更低的保费上。对保险公司非理赔成本（保险公司效率的一个代理指标）的探索性分析表明，随着市场中保险公司数量的增加，进入者的平均成本略有上升。这种模式不支持保费随着更多进入者而降低的假设，因为那些进入者效率更高，相反，这表明结果主要是由价格竞争驱动的。
