Is a composite score of physical performance measures more useful than usual gait speed alone in assessing functional status?

Overall physical performance can be represented by a composite score that is derived from upper and lower extremity performance measures. We aimed to identify whether composite scores of performance measures, particularly the lower extremity performance (LEP) score, upper extremity performance (UEP) score, and an overall score, are more accurate than usual gait speed (UGS) for assessing a wide range of functional status. We conducted a cross-sectional analysis on data from 701 community-dwelling older women (mean age 74.3 years). Trained testers measured UGS and the seven tests included in the composite scores. Using self-reported questionnaires, we assessed multiphasic functional status: physical function, higher-level functional capacity, mobility limitation, activities of daily living (ADLs), and falls. We compared the areas under the receiver operating characteristic curves (AUCs) of UGS with LEP, UEP, and overall scores for each status. We found no significant differences between the AUCs of UGS and LEP score for each status. The UEP score had significantly smaller AUCs for low physical function (0.73) and mobility limitation (0.78) than UGS alone (0.81 and 0.85, respectively), and the differences were substantial. Although the overall score had significantly greater AUCs for low higher-level functional capacity (0.83) and ADLs disability (0.83) than UGS alone (0.78 and 0.80, respectively), the differences were only 3-5%. The UGS should not be regarded solely as a measure of lower extremity function; this single test may represent overall physical performance. The UGS alone, which can be measured quickly and easily, suffice for assessing a wide range of functional status in older women.