Physical and functional measures predicting long-term mortality in community-dwelling older adults: a comparative evaluation in the Singapore Longitudinal Ageing Study.
Measures of functional status are known to predict mortality more strongly than traditional disease risk markers in old adult populations. Few studies have compared the predictive accuracy of physical and functional measures for long-term mortality. In this prospective cohort study, community-dwelling older adults (N = 2906) aged 55 + (mean age 66.6 ± 7.7 years) were followed up for mortality outcome up to 9 years (mean 5.8 years). Baseline assessments included Timed Up-and-Go (TUG), gait velocity (GV), knee extension strength, Performance Oriented Mobility Assessment, forced expiratory volume in 1 second, Mini-Mental State Examination (MMSE), Geriatric Depression Scale, frailty, and medical morbidity. A total of 111 (3.8%) participants died during 16976.7 person-years of follow up. TUG was significantly associated with mortality risk (HR = 2.60, 95% CI = 2.05–3.29 per SD increase; HR = 5.05, 95% CI = 3.27–7.80, for TUG score ≥ 9 s). In multivariate analysis, TUG remained significantly associated with mortality (HR = 1.64, 95% CI = 1.20–2.19 per SD increase; HR = 2.66, 95% CI = 1.67–4.23 for TUG score ≥ 9 s). In multivariable analyses, GV, MMSE, Frailty Index (FI) and physical frailty, diabetes and multi-morbidity were also significantly associated with mortality. However, TUG (AUC = 0.737) demonstrated significantly higher discriminatory accuracy than GV (AUC = 0.666, p < 0.001), MMSE (AUC = 0.63, p < 0.001), FI (AUC = 0.62, p < 0.001), physical frailty (AUC = 0.610, p < 0.001), diabetes (AUC = 0.582, p < 0.001) and multi-morbidity (AUC = 0.589, p < 0.001). TUG’s predictive accuracy shows surpassing predictive accuracy for long-term mortality in community-dwelling older adults.