Impacts of shifting responsibility for high-cost individuals on Health Insurance Exchange plan premiums and cost-sharing provisions.

Insurance companies can respond to increases in expected per-capita healthcare expenditures by adjusting premiums, cost-sharing requirements, and/or plan generosity. We use a Difference-in-Difference model with Plan-level Fixed Effects to estimate the impacts of increases in expected expenditures generated by closure of state-operated High Risk Pools (HRPs). For Silver plans, we find that issuers responded to HRP closures by increasing both premiums and deductibles, and by increasing the ratios of premiums to deductibles. This adjustment to the structure of plan prices is consistent with the hypothesis that issuers will be reluctant to adjust deductibles, because consumers tend to overweight changes in deductibles over changes in premiums. The increase in the ratio of premiums to deductibles indicates that the increase in expected expenditures triggered an increase in the share of total risk-pool healthcare expenditures paid by low healthcare utilizers, and a decrease in the share paid by high utilizers.