External validation of the minimal important change in the Berg Balance Scale scores of patients hospitalized for subacute stroke.

OBJECTIVE: To investigate the external validation of several reported minimal important change (MIC) values in the Berg Balance Scale (BBS) scores of patients with subacute stroke in a rehabilitation unit, in the overall cohort and walking-ability subgroups. DESIGN: Longitudinal study. SETTING: A rehabilitation unit. PARTICIPANTS: Patients with subacute stroke (n=286). INTERVENTION: Not applicable. MAIN OUTCOME MEASURE: The BBS, Functional Ambulation Categories (FAC), and Functional Independence Measure (FIM) were assessed at 30 days (baseline) and 60 days (follow-up) after stroke onset. BBS score changes between the baseline and follow-up were identified and categorized based on ≥2-, ≥5-, and ≥9-point thresholds. We divided the patients into pairs of groups based on FAC ≥1 or FIM ≥22 improvement. External validation was performed using the LR (likelihood ratio): LR+ >2.0 and LR- <0.5 were considered valid. We also divided the patients according to walking ability (FAC ≤2: assisted-walking group, FAC ≥3: unassisted-walking group), and external validation was repeated using the 5-point BBS MIC for the assisted-walking group and 4-point BBS MIC for the unassisted-walking group. RESULTS: The 5- and 2-point BBS MICs met the LR- criteria for both FAC and FIM improvements as anchors (5 pts: LR- = 0.48 [FAC], 0.46 [FIM]; 2 pts: LR- = 0.21 [FAC], 0.22 [FIM]); however, the 9-point BBS MIC did not. In the assisted-walking group, the 5-point BBS MIC also met the LR- criteria (LR- = 0.27 [FAC], 0.35 [FIM]). In the unassisted-walking group, the 4-point BBS MIC did not meet the criteria. CONCLUSION: The 5-point BBS MIC was applicable for patients with subacute stroke in a rehabilitation unit.