The fairness of the PPS reimbursement methodology.

In FY 1984 the Medicare program implemented a new method of reimbursing hospitals for inpatient services, the Prospective Payment System (PPS). Under this system, hospitals are paid a predetermined amount per Medicare discharge, which varies according to certain patient and hospital characteristics. This article investigates the presence of systematic biases and other potential imperfections in the PPS reimbursement methodology as revealed by its effects on Medicare operating ratios. The study covers the first three years of the PPS (approximately 1984-1986) and is based on hospital data from the Medicare cost reports and other related sources. Regression techniques were applied to these data to determine how Medicare operating ratios were affected by specific aspects of the reimbursement methodology. Several possible imbalances were detected. The potential undercompensation relating to these can be harmful to certain classes of hospitals and to the Medicare populations that they serve.