DEVELOPMENT OF FUNCTION-RELATED GROUPS VERSION 2.0 - A CLASSIFICATION-SYSTEM FOR MEDICAL REHABILITATION

Objective. To present a new version (2.0) of the Functional Independen ce Measure-Function Related Group (FIM-FRG) case-mix measure. Data Sou rce/Study Setting. 85,447 patient discharges from 252 freestanding fac ilities and hospital units contained in the 1992 Uniform Data System f or Medical Rehabilitation. Study Design. Patient: impairment category, functional status at admission to rehabilitation, and patient age wer e used to develop groups that were homogeneous with respect to length of stay. Within each impairment category patients were randomly assign ed to one data set to create the system (through recursive partitionin g) or a second set for validation. Clinical and statistical criteria w ere used to increase the percentage of patients classified, expand the impairment categories of FIM-FRGs Version 1.1, and evaluate the incre mental predictive ability of coexisting medical diagnoses. Predictive stability over time was evaluated using 1990 discharges. Principal Fin dings. In Version 2.0, the percentage of patients classified was incre ased to 92 percent. Version 2.0 includes two new impairment categories and separate groups for patients admitted to rehabilitation for evalu ation only. Coexisting medical diagnoses did not improve LOS predictio n. The system explains 31.7 percent of the variance in the logarithm o f LOS in the 1992 validation sample, and 31.0 percent in 1990 discharg es. Conclusions. FIM-FRGs Version 2.0 includes more specific impairmen t categories, classifies a higher percentage of patient discharges, an d appears sufficiently stable over time to form the basis of a payment system for inpatient medical rehabilitation.