Modifications of the FIM instrument under the inpatient rehabilitation facility prospective payment system

Area of Science:

• Rehabilitation Medicine
• Health Services Research
• Medical Economics

Background:

• The Functional Independence Measure (FIM) is a key tool for assessing patient function in inpatient rehabilitation.
• The Inpatient Rehabilitation Facility Prospective Payment System (IRF-PPS) was implemented in 2002, altering payment structures.
• Understanding changes in FIM data post-IRF-PPS is crucial for accurate patient outcome and resource utilization assessment.

Purpose of the Study:

• To detail modifications to the FIM instrument within the Inpatient Rehabilitation Facility-Patient Assessment Instrument (IRF-PAI).
• To compare FIM data for stroke patients before and after the 2002 IRF-PPS implementation.

Main Methods:

• Comparative analysis of Medicare patient data from 411 inpatient rehabilitation facilities (IRFs).
• Data spanned from 1998 to 2003, covering pre- and post-IRF-PPS periods.
• Year-by-year examination of FIM scores (motor and cognitive) for stroke patients.

Main Results:

• Pre-IRF-PPS: Slight decrease in admission motor FIM scores; stable discharge motor, admission cognitive, and discharge cognitive scores.
• Post-IRF-PPS (2001-2003): Significant decreases observed in all FIM ratings.
• Mean case-mix index increased from 1.39 to 1.49 due to lower admission FIM scores.

Conclusions:

• Decreased FIM ratings post-IRF-PPS may stem from altered coding practices or patient population changes.
• "Downcoding" to access higher payment categories is a potential factor.
• Careful consideration of coding changes is essential when comparing pre- and post-IRF-PPS FIM data.