Test-retest reliability and minimal detectable change for measures of balance and gait in adults with cerebral palsy

Abstract

BackgroundWalking and balance often begin to deteriorate in ambulant adults with cerebral palsy (CP) in early adulthood. The decline in walking and balance imposes a more sedentary lifestyle, increases falls risk, negatively affects health, participation, and quality of life, and ultimately results in increased disability. Available research is not sufficient to guide interventions to improve walking and balance in this population. To advance research in this area, there is a need for measures of gait and balance with proven psychometrics for adults with CP. Research questionThe goal of this study was to determine test-retest reliability and minimal detectable change (MDC) values and to assess score distribution for the Balance Evaluation Systems Test (BESTest) and the Four Square Step Test (FSST) as measures of balance, for the Activities-specific Balance Confidence (ABC) Scale and the Modified Fall Efficacy Scale (MFES) as measures of balance confidence, and for over-ground spatiotemporal gait parameters at comfortable gait speed (CGS) and fast gait speed (FGS). MethodsTwenty ambulant adults with CP (mean age 32.7 years), GMFCS-E&R Levels I and II, were tested twice within an average of 10 days. Test–retest reliability was evaluated using intra-class correlation coefficients (ICC2,1), and MDC95 values were calculated using standard error of measurement values. ResultsThe test-retest reliability of most outcome measures was good to excellent. ICC values were: BESTest = 0.99, BESTest sections 0.88 to 0.98, FSST = 0.91, ABC=0.86, MFES = 0.9, CGS = 0.88, and FGS = 0.98. MDC values were: BESTest total = 4.9%, BESTest sections 8.7%–21.2%, FSST = 3.7 s, ABC = 18%, MFES = 1 point, CGS = 0.26 m/s, and FGS = 0.14 m/s. Most outcome scores were broadly distributed over scales ranges. SignificanceAdults with CP demonstrated stable test-retest performance on the selected measures. These measures could be useful to assess balance and gait of adults with CP. The MDC values can help evaluate whether observed changes exceed the expected random test-retest variations.