Measurement characteristics of the Functional Independence Measure

Area of Science:

• Rehabilitation Medicine
• Psychometrics
• Biostatistics

Background:

• Clinicians and researchers require reliable and valid functional status measures with linear properties.
• Rasch rating scale analysis offers a method to convert raw scores into linear measures with quantifiable error.

Purpose of the Study:

• To investigate how clinicians perceive stroke rehabilitation patients compared to other patient groups using the Functional Independence Measure (FIM).
• To validate the FIM's motor and cognitive subscales for stroke patients using Rasch analysis.

Main Methods:

• Utilized Rasch rating scale analysis on the Functional Independence Measure (FIM) data.
• Analyzed the first 13 FIM items (motor function) and the last 5 FIM items (cognitive function) separately.
• Compared FIM ratings for stroke patients with those of other impairment groups.

Main Results:

• The FIM's motor items were rated similarly for stroke patients as for other impairment groups.
• Stroke patients exhibited distinct rating patterns on the FIM's cognitive items compared to many other groups.
• Provided tables for raw score to scaled measure conversions for motor and cognitive items across different impairment groups.

Conclusions:

• Measures derived from the FIM are confirmed to be linear and reliable across the instrument's range.
• The FIM effectively captures the unique functional characteristics of stroke patients, particularly on cognitive measures.
• Clinicians can confidently use FIM measures, understanding their linearity and sensitivity to specific patient populations.