Validade e confiabilidade das versões original e curta da escala Activities-Specific Balance Confidence (ABC-16 e ABC-6) para idosos brasileiros residentes na comunidade

Abstract

Introduction: Balance confidence is described as “a person’s ability to maintain balance while performing activities of daily living” and is affected by an individual’s beliefs. Therefore, an individual who report a low confidence in balance may present lower postural balance performances. One of the most used tools to quantify the balance confidence of the community-dwelling individual is the Activities-specific Balance Confidence (ABC) scale, in its original (ABC-16) and short (ABC-6) versions. The ABC scale was translated and adapted to the Brazilian older adults. However, the study of the psychometric properties is still required and also cut-off points for both scales have not been provided yet. Objectives: To investigate the psychometric properties of the ABC-16 and ABC-6, and to determine cut-off points capable to identity community-dwelling older adults with deficits in postural balance and higher risk of falling. Methods: This is a psychometric study that followed the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN). This study took place from April 2017 to November 2017. The level of balance confidence was assessed by the ABC-16 and ABC-6. To assess the interrater reliability, two evaluations with a 30-minute interval was performed by distinct evaluators. After one week, one of the evaluators re-applied the ABC-16 to verify the intrarater reliability. The order of the evaluators was chosen randomly. A third examiner assessed the postural balance of the individuals through the Berg Balance Scale (BBS), the modified Clinical Test of Sensory Interaction on Balance (mCTSIB) and the Unilateral Stance (US), the fear of falling through the Falls Efficacy Scale-International (FES-I), and mobility through the 4-m walk test (4MWT). Results: The ABC-16 and ABC-6 showed a statistically significant correlation with most of the measures of postural balance, FES-I and 4MWT. The ABC-6 also presented statistically significant correlation with the gold standard, the ABC-16 (r=0.958, p<0,001). The internal consistency analysis of the ABC-16 and ABC-6 yielded a Cronbach’s α value 0.943 and 0.901, respectively. Both ABC-16 and ABC-6 presented excellent intra and interrater reliability. The Receiver Operating Characteristics (ROC) curve indicated a value of ≤67% as the best cut-off point to identify older adults with balance impairments in the ABC-16 (sensitivity: 81%; specificity: 77.4%), and ≤44% (sensitivity: 87.5%; specificity: 82.1%) in the ABC-6. Conclusion: Both ABC-16 and ABC-6 have an overall good validity, and excellent internal consistency, and intra and inter-rater reliability. Therefore, these scales are suitable tools for assessing balance confidence in the Brazilian community-dwelling elderly people.