Unrecognized redistributions of revenue in diagnosis-related group-based prospective payment systems.

The Medicare prospective payment system, which is based on the diagnosis-related group patient-classification system, identifies previously unrecognized redistributions of revenue among diagnosis-related groups and hospitals. The redistributions are caused by two artifacts. One artifact results from the use of labor market indexes to adjust costs for the different prices paid by hospitals in different labor markets. The other artifact results from the use of averages that are based on the number of hospitals, not the number of patients, to calculate payment rates from average costs. The effects of these artifacts in a sample data set have been measured, and it was concluded that they lead to discrepancies between costs and payments that may affect hospital incentives--the overall payment for each diagnosis-related group--and Medicare's total payment.