Interrater and Test-Retest Reliability and Minimal Detectable Change of the Balance Evaluation Systems Test (BESTest) and Subsystems With Community-Dwelling Older Adults
Authors: Wang-Hsu Elizabeth , Smith Susan S. 
Published: January 2017

Background and Purpose:
Falls are a common cause of injuries and hospital admissions in older adults. Balance limitation is a potentially modifiable factor contributing to falls. The Balance Evaluation Systems Test (BESTest), a clinical balance measure, categorizes balance into 6 underlying subsystems. Each of the subsystems is scored individually and summed to obtain a total score. The reliability of the BESTest and its individual subsystems has been reported in patients with various neurological disorders and cancer survivors. However, the reliability and minimal detectable change (MDC) of the BESTest with community-dwelling older adults have not been reported. The purposes of our study were to (1) determine the interrater and test-retest reliability of the BESTest total and subsystem scores; and (2) estimate the MDC of the BESTest and its individual subsystem scores with community-dwelling older adults.

Methods:
We used a prospective cohort methodological design. Community-dwelling older adults (N = 70; aged 70-94 years; mean = 85.0 [5.5] years) were recruited from a senior independent living community. Trained testers (N = 3) administered the BESTest. All participants were tested with the BESTest by the same tester initially and then retested 7 to 14 days later. With 32 of the participants, a second tester concurrently scored the retest for interrater reliability. Testers were blinded to each other's scores. Intraclass correlation coefficients [ICC(2,1)] were used to determine the interrater and test-retest reliability. Test-retest reliability was also analyzed using method error and the associated coefficients of variation (CVME). MDC was calculated using standard error of measurement.

Results:
Interrater reliability (N = 32) of the BESTest total score was ICC(2, 1) = 0.97 (95% confidence interval [CI], 0.94-0.99). The ICCs for the individual subsystem scores ranged from 0.85 to 0.94. Test-retest reliability (N = 70) of the BESTest total score was ICC(2,1) = 0.93 (95% CI, 0.89-0.96). ICCs for the individual subsystem scores ranged from 0.72 to 0.89. The CVME (N = 70) of the BESTest total score was 4.1%. The CVME for the subsystem scores ranged from 5.0% to 10.7%. MDC (N = 70) for the BESTest total score at the 95% CI was 7.6%, or 8.2 points. MDC at the 95% CI for subsystem scores ranged from 11.7% to 19.0% (2.1-3.4 points).

Discussion:
Results demonstrated generally good to excellent interrater and test-retest reliability in both the BESTest total and subsystem scores with community-dwelling older adults.

Conclusions:
The BESTest total and individual subsystem scores demonstrate good to excellent interrater and test-retest reliability with community-dwelling older adults. A change of 7.6% (8.2 points) or more in the BESTest total and a percentage change ranged from 11.7% to 19.0% (2.1-3.4 points) in the subsystem scores are suggested for clinicians to be 95% confident of true change when evaluating change in this population.