Use of a short version of the Activities-specific Balance Confidence scale in multiple sclerosis

Background: Multiple sclerosis (MS) is a neurologic disease that results in balance and mobility impairments that are associated with elevated fall risk. One common patient-reported outcome measure of balance is the 16-item Activities-specific Balance Confidence (ABC) scale. The ABC scale is valid and reliable in assessing balance confidence in people with MS. However, a shorter, six-question version of the ABC scale, the ABC-6 scale, has been proposed to save time in a clinical setting. Thus, we assessed the convergent validity and internal consistency reliability of the ABC-6 scale in people with MS. Methods: A total of 221 participants were included in this secondary analysis to compare the ABC-6 scale with the ABC scale. Convergent validity and internal consistency reliability were applied to participants based on fall history and physiological fall risk. Results: Statistical analysis indicated a main effect of group of the ABC and ABC-6 scales (P < .001). Both scales showed good to very good internal consistency (Cronbach α range, 0.832-0.975) and good reliability (intraclass correlation coefficient score range, 0.888-0.941). Furthermore, both versions had moderate convergent validity. Sensitivity ranged from 30% to 97%, and specificity ranged from 64% to 100% across groups tested. Conclusions: The ABC and ABC-6 scales demonstrated good internal consistency reliability and moderate convergent validity in predicting balance confidence in people with MS. However, poor sensitivity of both versions in distinguishing between MS groups at risk for falls may call into question the usefulness of this self-report measure.