Optimal payment systems for health services.

Demand-side cost sharing and the supply-side reimbursement system provide two separate instruments that can be used to influence the quantity of health services consumed. For risk-averse consumers, optimal payment systems--pairs of insurance and reimbursement plans--are characterized by conflict rather than consensus between patient and provider about the quantity of treatment. A model of conflict resolution based on bargaining theory is used to represent the outcome when the payment system creates divergences between desired demand and desired supply. Using that model, we describe the optimal combination of insurance and reimbursement systems that maximize consumer welfare.