Provider behavior under prospective reimbursement. Cost sharing and supply.

This paper develops a model in which physicians choose the level of services to be provided to their patients. We show that if physicians undervalue benefits to patients relative to hospital profits, prospective payment, a system in which hospitals receive a payment dependent on the diagnosis-related group within which a patient falls, can lead to too few services being provided. In contrast, a 'cost-based' reimbursement system is shown to result in too many services being provided. Competition between hospitals for physicians will tend to augment both of these problems. We also examine a mixed reimbursement system, in which hospital reimbursements are paid partly prospectively and partly cost-based. This system is shown under a variety of circumstances to be superior to the other two reimbursement systems by improving the incentives for the efficient level of services, reducing incentives to unnecessarily admit or reclassify patients, and reducing risk to providers.