Mobility stress test approach to predicting frailty, disability, and mortality in high-functioning older adults

Objectives To examine the validity of the Walking While Talking Test (WWT), a mobility stress test, to predict frailty, disability, and death in high-functioning older adults. Design Prospective cohort study. Setting Community sample. Participants Six hundred thirty-one community-residing adults aged 70 and older participating in the Einstein Aging Study (mean follow-up 32 months). High-functioning status at baseline was defined as absence of disability and dementia and normal walking speeds. Measurements Hazard ratios (HRs) for frailty, disability, and all-cause mortality. Frailty was defined as presence of three out of the following five attributes: weight loss, weakness, exhaustion, low physical activity, and slow gait. The predictive validity of the WWT was also compared with that of the Short Physical Performance Battery (SPPB) for study outcomes. Results Two hundred eighteen participants developed frailty, 88 developed disability, and 49 died. Each 10-cm/s decrease in WWT speed was associated with greater risk of frailty (HR = 1.12, 95% confidence interval (CI) = 1.06-1.18), disability (HR = 1.13, 95% CI = 1.03-1.23), and mortality (HR = 1.13, 95% CI = 1.01-1.27). Most associations remained robust even after accounting for potential confounders and gait speed. Comparisons of HRs and model fit suggest that the WWT may better predict frailty whereas SPPB may better predict disability. Conclusion Mobility stress tests such as the WWT are robust predictors of risk of frailty, disability, and mortality in high-functioning older adults.