Cognitive Impairment, Chronic Medical Illness, and Risk of Mortality in an Elderly Cohort

Abstract

The mortality risk for older persons with chronic medical illness and cognitive impairment is relatively unknown. The authors assessed 6-year mortality risks for cognitive impairment and six chronic diseases in 7,482 subjects from the East Boston, Massachusetts, and rural Iowa cohorts of the Established Populations for Epidemiologic Studies in the Elderly (EPESE). Cognitive impairment was identified with a modified form of Pfeiffer's Short Portable Mental Status Questionnaire. Chronic medical illnesses included diabetes, stroke, myocardial infarction, hypertension, hip fracture, and cancer. The authors examined the association of cognitive impairment and each of the six chronic illnesses with mortality by means of Cox proportional-hazards regression models, and determined the interaction of cognitive impairment and chronic medical illness on mortality. Participants who were cognitively impaired at baseline were found to have a 68% increased relative risk of mortality. The relative risks of mortality from diabetes, heart attack, stroke, and hip fracture were similar to the risk from cognitive impairment. Interactions between cognitive impairment and each chronic medical illness on mortality were not statistically significant. Survival curves demonstrate that the effects of cognitive impairment and chronic medical illness on mortality are mostly additive, resulting in very poor survival for those with both medical illness and cognitive impairment. Further research should examine the healthcare behaviors and needs of older adults with cognitive impairment.