Classifying rehabilitation inpatients by expected functional gain

Abstract

Objectives: To create a more suitable payment system for medical rehabilitation, the authors developed a companion classification system to the original functional independence measure-function-related groups (FIM-FRGs), which classify patients having similar lengths of stay in a rehabilitation hospital or inpatient unit. The companion system presented here groups patients according to their gains in functional status during the rehabilitation stay.

Methods: Data from 84,492 patients discharged from 252 rehabilitation facilities in 1992 were provided by the Uniform Data System for Medical Rehabilitation. Classification rules were formed using clinical judgment and a recursive partitioning algorithm. The gain-FRGs system used four predictor variables: (1) diagnosis leading to disability, admission scores on the (2) motor and (3) cognitive subscales of the FIM, and (4) patient age.

Results: The gain-FRGs system contained 74 patient groups and explained 21% of the variation in functional gain for patients in a different set of records withheld for validation.

Conclusions: The gain-FRGs system should be considered for prospective payment systems because it gives the provider an incentive to improve patient outcomes, which is missing in a payment system based on FIM-FRGs alone.