The Activities-specific Balance Confidence scale: reliability and validity in Spanish patients with vestibular disorders

Purpose: To examine the reliability and validity of the Spanish version of the Activities-specific Balance Confidence scale (ABC-S), and its ability to discriminate between patients with and without a history of falls among a Spanish population with vestibular disorders. Method: A total of 84 participants completed the ABC-S. Internal consistency, test-retest reliability and construct validity (exploratory factor analysis) were analysed. Concurrent validity was evaluated using the 12-item Short Form Health Survey (SF-12) and the Dizziness Handicap Inventory (DHI). To determine the accuracy of the ABC total score in discriminating patients with and without a history of falls, a receiver operating characteristic (ROC) curve analysis was performed. Results: The ABC-S showed excellent internal consistency (Cronbach's alpha=0.916) and substantial test-retest reliability (ICC=0.86, 95% CI: 0.74-0.93), with standard error and minimal detectable change values of 8.64 and 16.94, respectively. Factor analyses suggested a three-factor structure (explained variance was 62.24%). The ABC total score significantly correlated with the physical component summary score of the SF-12 and with the DHI-P, DHI-E, DHI-F and DHI total scores (p<0.001). The ABC-S was significantly able to discriminate between participants with and without a history of falls (p<0.006). Conclusions: The ABC-S is a valid and reliable instrument, suitable to assess balance confidence in Spanish patients with vestibular disorders. Implications for Rehabilitation The Spanish version of the ABC scale is a valid and reliable measure of balance confidence in patients with vestibular disorders. In persons with vestibular disorders, the Spanish version of the ABC scale has shown the ability to discriminate between patients with and without a history of falls in the last year.