Declining energy predicts incident mobility disability and mortality risk in healthy older adults
Briana N. Sprague, Xiaonan Zhu, Rebecca Ehrenkranz, Qu Tian, Theresa Gmelin, Nancy W. Glynn, Andrea Rosso, Caterina Rosano
Abstract
BACKGROUND: The purpose was to examine whether longitudinal changes in self-reported energy predict incident mobility disability and mortality. We further explored whether changes in energy-related behaviors (physical activity, appetite, or sleep quality) would explain these associations. METHODS: N = 2021 participants from the Health, Aging and Body Composition Study free from mobility disability and with at least three energy assessments from years 2 to 10. MEASUREMENTS: The outcomes were time to first self-reported inability to walk a quarter of a mile (mobility disability) and death. Self-reported energy level (SEL) was a single-item indicator over the prior month, ranging from 0 to 10; person-specific slopes measured whether individuals increased or decreased in SEL across the total follow-up time (mean 7.09 years, +1.72, range 2-8 years). Potential energy-related mediators were baseline and change in self-reported physical activity, appetite, and sleep quality. Covariates were baseline levels and change in demographics, health characteristics and behaviors, tiredness, cognition, mood, and gait speed. RESULTS: A total of 947 developed disability and 567 died over the study follow-up. A one-point change in SEL over the follow-up (or an average 0.125 points/year) was inversely associated with a 35% risk of incident mobility disability (hazard ratio = 0.65, 95% confidence interval [CI] = 0.55, 0.76, p < 0.001) and 33% risk of death (hazard ratio = 0.67, 95% CI = 0.42, 0.87, p = 0.003), independent of covariates. Potential energy-related mediators did not attenuate this association. CONCLUSIONS: In this longitudinal analysis of community-dwelling older adults, energy decline was common and a significant independent predictor of disability risk and mortality.