RESUMO
OBJECTIVE: The aim of this study was to establish the internal consistency and construct validity of the Activities-specific Balance Confidence (ABC) Scale and ABC-6 in adults from the general population with concussion. DESIGN: Prospective analysis. SETTING: Outpatient concussion care clinic. PARTICIPANTS: Adults from the general population with concussion referred to a concussion care clinic within 7 days of injury (N=511). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Balance confidence was assessed with the Activities-specific Balance Confidence (ABC) Scale and the ABC-6. Concussion symptoms were characterized using the Sport Concussion Assessment Tool version 5 (SCAT5) symptom checklist. Instrumented measures of balance and gait included center of pressure velocity and double support time, respectively. Balance was also assessed using the mBESS. RESULTS: The ABC and ABC-6 were strongly correlated (ρ=0.980, P<.001). Cronbach α for ABC and ABC-6 was 0.966 and 0.940, respectively. Factor analysis verified the existence of 2 components of the ABC, 1 including all items of the ABC-6 as well as 3 additional items. ABC and ABC-6 were moderately significantly correlated with SCAT5 symptom number, severity, and symptom domain (ρ=-0.350 to -0.604). However, correlations between ABC and ABC-6 with instrumented measures of balance and gait were not statistically significant, except for double support time during dual-task gait with ABC-6 (ρ=-0.218). CONCLUSIONS: In community-dwelling adults with concussion, the ABC and ABC-6 have good internal consistency. Convergent validity is stronger for symptom endorsement measures within SCAT5 domains, which has a similar construct (subjectivity) to balance confidence. Both the ABC and ABC-6 are valid measures of balance self-efficacy in adults from the general population with concussion. The ABC-6 may be a useful tool for characterizing the effect of concussion on perceptions of the ability to perform functional tasks that challenge balance and mobility.