Discriminant Analysis of the Patient-Specific Functional Scale in Discerning Between Loss of Physical Function Categories in Community-Dwelling Older Adults

Previous research indicates that the Patient-Specific Functional Scale (PSFS) is a reliable and valid measure of loss of physical function in community-dwelling older adults. However, the ability of the PSFS to classify community-dwelling older adults into categories of loss of physical function has not been investigated. The purpose of this study was to investigate the ability of the PSFS to discern between different categories of physical function loss in community-dwelling older adults. Thirty-one community-dwelling older adults (mean age = 81.1 years; SD = 8.3) completed a set of physical function questionnaires: the PSFS, the Lower Extremity Functional Scale (LEFS), and the Activities-specific Balance Confidence (ABC) scale. Study participants also completed the Short Physical Performance Battery (SPPB). Scores on the PSFS, LEFS, ABC scale, and SPPB were divided into loss of physical function categories (mild, moderate, severe, and very severe). Discriminant analysis was used to determine the ability of the PSFS to discern between the different categories of loss of physical function. The canonical correlation between the eigenvalues and classifications for the LEFS, ABC scale, and SPPB was 0.85 (P < .001), 0.72 (P < .001), and 0.40 (P = .18), respectively. The findings of this investigation indicate that the PSFS has predictive ability to classify community-dwelling older adults into categories of loss of physical function, based on LEFS and ABC scale classifications, which could be important for purposes such as evaluation, screening, and measuring clinically important differences in loss of physical function.