The Minimal Detectable Change for Balance and Balance Confidence After Chronic Spinal Cord Injury

Balance and balance confidence are often impaired in ambulatory individuals with incomplete spinal cord injury (iSCI) and can increase the risk for falls. The Berg Balance Scale (BBS) and the Activities-specific Balance Confidence (ABC) Scale assess balance and balance confidence, respectively, although clinically significant changes in these outcomes are uncertain. Accordingly, the goal of this study was to determine the minimal detectable change (MDC) for the BBS and ABC Scale in individuals after iSCI.

Individuals >6 months after C1-T10 iSCI with walking speeds <1.0 m/s were recruited and self-identified as community ambulators or community wheelchair users. Using a population-specific standardization protocol, the BBS and ABC Scale were administered twice by varied assessors. Test-retest reliability was assessed using the intraclass correlation coefficient with absolute agreement. The MDC was calculated with 95% confidence and stratified by the primary means of community mobility.

Of the 50 individuals included, 52% identified as community ambulators. Both the BBS and ABC Scale demonstrated excellent test-retest reliability. Overall, the MDC 95 for the BBS was 8.0 points and lower for self-identified community ambulators (5.4 points) than for community wheelchair users (10.3 points). Observed MDC 95 for the ABC Scale was 16.6% and was similar for community ambulators (15.6%) and community wheelchair users (17.5%).

Using a population-specific standardization protocol, the BBS and ABC Scale demonstrated excellent test-retest reliability in iSCI. The obtained MDC for the BBS is slightly higher than those reported in other neurologic populations, although the MDC for the ABC Scale is similar.