Determination of the minimal clinically important difference in the FIM instrument in patients with stroke.

Objective: To define the minimal clinically important difference (MCID) for the FIM instrument in patients poststroke.

Design: Prospective case series discharged over a 9-month period.

Setting: Long-term acute care hospital.

Participants: Patients with stroke (N=113).

Interventions: Not applicable.

Main Outcome Measures: Admission, discharge, and change scores were calculated for the total FIM, motor FIM, and cognitive FIM. Assessments of clinical change were rated at discharge on a 15-point (-7 to +7) Likert scale by attending physicians, with MCID defined at a cutoff score of 3. The FIM change scores associated with MCID were identified from receiver operating characteristic curves. Bayesian analysis was used to determine the probability of individual patients achieving MCID.

Results: FIM change scores associated with MCID were 22, 17, and 3 for the total FIM, motor FIM, and cognitive FIM, respectively. The accuracy of the MCID was greater when subjects were categorized based on admission FIM scores than when considering the sample as a whole. Larger FIM change scores were related to MCID in subjects with lower admission FIM scores.

Conclusions: These findings will assist in the interpretation of FIM change scores relative to physicians' assessments of important clinical change.