The design of insurance coverage for medical products under imperfect competition
 

This paper studies the design of health insurance with ex post moral hazard, when there is imperfect competition in the market for the medical product. Various scenarios, such as monopoly pricing, price negotiation or horizontal differentiation are considered. The insurance contract specifies two types of copayments: an ad valorem coinsurance rate and a specific (per unit) copayment. By combining both copayment rates in an adequate way the insurer can effectively control the producer price, which is then set so that the producer´s revenue just covers …fixed costs. Consequently, a suitable regulation of the copayment instruments leads to the same reimbursement rule of individual expenditures as under perfect competition for medical products. Additional rationing of coverage because of imperfect competition as advocated by Feldstein (1973) is thus not necessary. Interestingly the optimal policy closely resembles a reference price mechanism in which copayment rates are low (possibly negative) and coinsurance rates are high.

We determine the optimal health policy mix when the average utility of patients increases with the supply of drugs available in a therapeutic class. Health risk coverage rely on two instruments, copayment and reference pricing, that affect the supported risk composed by health expenses and diversity of treatment. For a fixed supply of drugs, the reference pricing policy aims at minimizing expenses in which case, the equilibrium price of drugs is independent of the copayment rate. However, with endogenous supply of drugs, diversity of treatment may susbtitute for insurance so that the reference pricing may depart from maximal cost-containement to promote entry. We then analyse the determinents of the optimal policy. While an increase in risk aversion or in the side effect loss increases diversity and decreases the copayment rate, an increase in entry cost both decreases diversity and the copayment rate.