Inflammation, Depression, and Slow Gait: A High Mortality Phenotype in Later Life

Abstract

Background: Inflammation, slow gait, and depression individually are associated with mortality, yet little is known about the trajectories of these measures, their interrelationships, or their collective impact on mortality.

Methods: Longitudinal latent class analysis was used to evaluate trajectories of depression (Center for Epidemiologic Studies Depression ≥ 10), slow gait (<1.0 m/s), and elevated inflammation (interleukin 6 > 3.2 pg/mL) using data from the Health Aging and Body Composition Study. Logistic regression was used to identify their associations with mortality.

Results: For each outcome, low-probability (n inflammation = 1,656, n slow gait = 1,471, n depression = 1,458), increasing-probability (n inflammation = 847, n slow gait = 880, n depression = 1,062), and consistently high-probability (n inflammation = 572, n slow gait = 724, n depression = 555) trajectories were identified, with 22% of all participants classified as having increasing or consistently high-probability trajectories on inflammation, slow gait, and depression (meaning probability of impairment on each outcome increased from low to moderate/high or remained high over 10 years). Trajectories of slow gait were associated with inflammation (r = .40, p < .001) and depression (r = .49, p < .001). Although worsening trajectories of inflammation were independently associated with mortality (p < .001), the association between worsening trajectories of slow gait and mortality was only present in participants with worsening depression trajectories (p < .01). Participants with increasing/consistently high trajectories of depression and consistently high trajectories of inflammation and slow gait (n = 247) have an adjusted-morality rate of 85.2%, greater than all other classification permutations.

Conclusions: Comprehensive assessment of older adults is warranted for the development of treatment strategies targeting a high-mortality risk phenotype consisting of inflammation, depression, and slow gait speed.

Keywords: Depression; Frailty; Inflammation; Mortality; Slow Gait.