Responsiveness of the Falls Efficacy Scale-International and Activities-Specific Balance Confidence Scale in Parkinson’s disease

OBJECTIVE: This study aimed to establish the minimal clinically important difference (MCID), minimal detectable change (MDC), and substantial clinical benefit (SCB) values for the Falls Efficacy Scale-International (FES-I) and the Activities-specific Balance Confidence (ABC) scales in people with Parkinson's disease (PwPD). METHODS: A total of 119 PwPD completed an intervention program. Fear of falling and balance confidence were assessed before and after the intervention using the FES-I and ABC scale, along with the Global Rating of Change (GRoC). RESULTS: Anchor-based analyses identified MCIDs of -5.7 points for FES-I and 9.6% for the ABC scale. SCBs were determined as -17.4 points for FES-I and 24.7% for the ABC scale using the mean-difference method. Receiver operating characteristic (ROC) analyses yielded optimal MCID cutoffs of ≥ -2 for FES-I and ≥ +5% for ABC scale, and SCB cutoffs of ≥ -10 for FES-I and ≥ +7.5% for ABC scale, all with high sensitivity and specificity. Distribution-based MDC estimates ranged from 2.7-7.4 points for FES-I and 4.7-13.1% for the ABC scale. CONCLUSION: This study provides robust MCID, MDC, and SCB estimates for FES-I and ABC scale in PwPD, offering clinically meaningful benchmarks to guide interpretation of change and evaluate the effectiveness of balance and fear-of-falling interventions.