The story of function-related groups--please, first do no harm

In November 2000, the Health Care Financing Administration (HCFA) published a proposed rule announcing their intention to implement a prospective payment system for rehabilitation inpatient facilities and hospital units. In this system, payments are to be scaled to patient complexity through a classification system referred to as case-mix groups (CMGs) modeled after the Functional Independence Measure-Function Related Groups, which were developed from the FIM instrument. Under the HCFA proposal, CMGs will be derived from the Minimum Data Set for Post-Acute Care (MDS-PAC). This shift to the MDS-PAC, with little scientific evidence to support it, can have a negative impact on how the system expresses patient need, on how patients access services, and on the equity of hospital payments.