Reliability, validity, and agreement of the short-form Activities-specific Balance Confidence Scale in people with lower extremity amputations

Background: Clinicians use the Activities-specific Balance Confidence Scale to understand balance confidence. A short-form Activities-specific Balance Confidence scale, was developed using the six most difficult tasks from the original Activities-specific Balance Confidence scale; however, short-form the short-form scale psychometrics and agreement with the original scale have yet to be explored in people with lower extremity amputations. Objective: To determine the relative and absolute reliability, construct validity, and agreement of the short-form Activities-specific Balance Confidence scale. Study design: Test–retest with a 2-week interval. Methods: Analysis for relative reliability and internal consistency was intraclass correlation coefficient and Cronbach’s α, respectively. Absolute reliability was measured using standard error of measurement and minimal detectable change. Bland–Altman plots measured agreement between scales. Construct validity was evaluated against the L Test using a Pearson-product moment correlation. Results: The short-form Activities-specific Balance Confidence (intraclass correlation coefficient = 0.92) and Activities-specific Balance Confidence (intraclass correlation coefficient = 0.91) scales had excellent relative reliability. Both scales demonstrated good internal consistency. Worse absolute reliability was observed in the short-form Activities-specific Balance Confidence scale. Construct validity against the L Test was confirmed. Bland–Altman plots indicated poor agreement between scales. Conclusion: Both scales exhibit excellent relative reliability and good internal consistency and construct validity. Poor agreement between short-form Activities-specific Balance Confidence and Activities-specific Balance Confidence indicates the scales should not be used interchangeably. Inadequate absolute reliability of the short-form Activities-specific Balance Confidence scale suggests the Activities-specific Balance Confidence should be the balance confidence scale of choice. Clinical relevance: Balance confidence is an important metric for our understanding of rehabilitation and community re-integration in people with lower extremity amputations. Due to inferior absolute reliability and a lack of appropriate items composing the short-form Activities-specific Balance Confidence scale, the full-scale Activities-specific Balance Confidence is recommended for the assessment of balance confidence in this population.