Comparison of muscle strength and power in the short physical performance battery for predicting negative outcomes in older adults with mobility limitations

Objectives: The present study examined sex-specific associations between Short Physical Performance Battery (SPPB) indexes operationalized according to lower limb muscle strength and power and the occurrence of negative events in older adults with mobility limitations. Design: Secondary longitudinal analysis of a randomized controlled trial Setting: Community-Dwellers. Participants: Older adults (70+ years) with mobility limitations. Methods: Participants completed the SPPB under standardized conditions. Muscle power measures were estimated according to results of the 5-time sit-to-stand (5STS) test using validated equations. Then, four SPPB indexes were created by replacing 5STS test results with muscle power measures. Outcomes were assessed after 24 months of randomization and included mobility disability, hospitalization, and death. Results: Data from 1,422 participants were analyzed. Cox regression models revealed sex-specific associations between SPPB variants and adverse outcomes. SPPB indexes incorporating muscle strength or power were significantly associated with mobility disability in both sexes, and with hospitalization and death in women. According to Akaike's Information Criterion, muscle power-based SPPB indexes provided the best fit for predicting negative outcomes. Conclusions: Sex-specific associations exist between modified SPPB indexes and adverse outcomes in older adults with mobility limitations. Notably, SPPB variants incorporating muscle power measures demonstrated the best fit for adverse outcomes in comparison to traditional SPPB. Trial registration: ClinicalTrials.gov identifier: NCT02582138 (registration date: 2015-10-08).