Cognitive Performance Concomitant With Vision Acuity Predicts 13-Year Risk for Mortality

Objectives: To assess the joint impact of cognitive performance and visual acuity on mortality over a 13-year follow-up in a representative U.S. sample. Methods: Data from NHANES participants (> 18 years old) were linked with the death record data of the National Death Index (NDI) with mortality follow-up through December 31, 2011. Cognitive performance was evaluated by the Digit Symbol Substitution Test (DSST) and cognitive performance impairment was defined as the DSST score equal to or less than the median value in the study population. Visual impairment was defined as presenting visual acuity worse than 20/40 in the better-seeing eye. Risks of all-cause and specific-cause mortality were estimated with Cox proportional hazards models after adjusting for confounders. Results: A total of 2,550 participants 60 years and older from two waves of National Health and Nutrition Examination Survey (NHANES: 1999-2000 & 2001-2002) were included in the current analysis. Over a median follow-up period of 9.92 years, 952 (35.2%) died of all causes, of whom 239 (23.1%), 224 (24.0%) and 489 (52.9%) died from cardiovascular disease (CVD), cancer and non-CVD/non-cancer mortality, respectively. Cognitive performance impairment and visual impairment increased the odds for mortality. Co-presence of visual impairment among cognitive impaired elderly persons predicted nearly a 3-fold increased risk of all-cause mortality (Hazard Ratios (HR), 2.74; 95% confidence interval (CI), 2.02-3.70; P < 0.001) and almost a 4-fold higher risk of non-CVD/non-cancer mortality (HR, 3.72; 95% CI, 2.30-6.00; P < 0.001) compared to having neither impairment. Conclusions: People aged 60 years and over with poorer cognitive performance were at higher risk of long-term survival, and are especially vulnerable to further mortality when concomitant with visual impairment. It is informative for clinical implication in terms of early preventive interventions.