Zwart Gijsbert
University of Groningen, EEF and FEBRI, The Netherlands.
J Health Econ. 2025 Jan;99:102955. doi: 10.1016/j.jhealeco.2024.102955. Epub 2024 Dec 11.
We analyse a model of optimal risk adjustment in competitive health-insurance markets which suffer from both ex-ante adverse selection and ex-post moral hazard. We find, firstly, that, unlike in an adverse-selection-only market, in an environment where also moral hazard is important, removing insurers' selection incentives requires risk-adjustment payments that do not fully equalize costs among consumer types. Current practice of attempting to correct for all predictable cost differences among consumers is then misguided. Secondly, if the sponsor of the risk-adjustment system is not only concerned with eliminating selection distortions, but also wants to redistribute towards high-risk consumers, the required higher risk-adjustment payments will introduce selection distortions in high-risk consumers' contracts. This leads to excessive equilibrium provision of care for those suffering severe health shocks. Finally, insurer market power creates countervailing incentives, helping the risk adjuster to combat selection distortions but working against a risk-adjustment regulation that also cares about redistribution.
我们分析了竞争激烈的健康保险市场中的最优风险调整模型，该市场同时存在事前逆向选择和事后道德风险。首先，我们发现，与仅存在逆向选择的市场不同，在道德风险也很重要的环境中，消除保险公司的选择激励需要风险调整支付，而这种支付并不能完全平衡不同消费者类型之间的成本。因此，当前试图纠正消费者之间所有可预测成本差异的做法是错误的。其次，如果风险调整系统的发起者不仅关心消除选择扭曲，还希望向高风险消费者进行再分配，那么所需的更高风险调整支付将在高风险消费者的合同中引入选择扭曲。这会导致对遭受严重健康冲击的人群提供过度的均衡医疗服务。最后，保险公司的市场力量产生了抵消性激励，有助于风险调整者对抗选择扭曲，但不利于同时关注再分配的风险调整监管。
