External validation of abbreviated versions of the activities-specific balance confidence scale in Parkinson's disease.

Balance confidence, measured using the Activity-Specific Balance Confidence Scale (ABC-16), can affect quality of life in individuals with Parkinson's disease (PD). Two abbreviated 6-item versions of the ABC-16 have been previously derived to measure balance confidence in an expedited fashion. This study aimed to validate these abbreviated versions and to determine their correlations with measures of balance and functional capacity. Eighty-nine individuals with PD participated in the study. Using the 25th percentile, five items were identified as the lowest scoring items (i.e., lowest balance confidence), and thus a 5-item version of the questionnaire was created. Internal consistency and the relationship with the ABC-16 were good for all abbreviated versions (Cronbach alpha > 0.93; ICC > 0.91). All versions correlated significantly with most measures of balance and function, with no differences between versions. An abbreviation of the ABC-16, using only five items, may prove useful in busy clinical and research settings.