Purpose:
To examine the relationship between vision, exercise, and mortality in the aging U.S. adult population by testing the association of self-rated vision and self-rated vigorous physical activity trajectories over time and the association of these trajectories with mortality.
Methods:
Using respondents from five cohorts in the Health and Retirement Survey (HRS) (n=28,474) linked to mortality data through the National Death Index with follow-up through 2006, structural equation modeling with latent variables is used to estimate non-linear trajectories for exercise and eyesight between 1996 - 2006 and the association between these trajectories. Factor scores for individual respondent’s intercepts, slopes, and quadratic terms are used in the full model of mortality depicted in Figure 1. Multiple imputation for missing data was used.
Results:
Controlling for unobserved, time-invariant characteristics of individuals and specific, time-varying characteristics including age, BMI, smoking, and multiple health conditions, vision and exercise are positively correlated in 1996 (r=0.17), average changes in vision and exercise between 1996 and 2006 are positively correlated (r=0.15), and the rates of these changes are positively correlated (r=0.15). This indicates that declines and rates of decline in vision are related to declines and rates of decline in exercise. Worse vision (1 point lower on a 5-point scale) across persons in 1996 increases the hazard of death [HR=1.61; 95% CI: (1.26, 2.05)]. An average decrease of one point in vision within a person over a two year period would increase mortality hazard by a factor of 16 [HR=16.34; 95% CI: (2.20, 121.64)]. Exercise in 1996 decreases mortality risk [HR=0.76; 95% CI: (0.62, 0.93)].
Conclusions:
Vision and exercise are related to one another and to mortality after controlling for all fixed person characteristics and changing person characteristics including major confounding health conditions lending more robust support to causal connections than can be obtained from cross-sectional associations.
Keywords: aging • low vision