Frailty and cognitive impairment as predictors of mortality in older Mexican Americans

Objective: Examine the association between frailty and cognitive impairment as predictors of mortality over a 10-year period in a selected sample of older mexican americans. Design: Longitudinal analyses using data from the hispanic established populations for the epidemiologic Study of the elderly (1995-96/2004-05). Setting: Five southwestern states: Texas, new mexico, Colorado, arizona, and California. Participants: Mexican Americans aged 67 and older with complete information on the frailty index and the mini mental State examination (MMSE) (n=1,815). Measurements: Cognitive impairment determined by a score in the MMSE < 21. Frailty defined as three or more of the following components: 1) weight-loss, 2) weakness, 3) self-reported exhaustion, 4) slow walking speed, and 5) low physical activity level. Sociodemographic characteristics and chronic medical conditions were used as covariates. Mortality was determined using the national death index or by proxy. Results: As MMSE score declines over time, the percent of frail individuals increases in a linear fashion. Frailty and cognitive impairment are independent risk factors for mortality after controlling for all covariates (HR 2.03 95% CI 1.57-2.62; HR 1.26 95% CI 1.05-1.52, respectively). When both cognitive impairment and frailty were added to the model, HR for individuals with cognitive impairment was no longer statistically significant. Conclusion: The relation between frailty and cognitive impairment needs careful analysis in this population to establish pathways increasing mortality and decreasing quality of life. Our results suggest frailty is a stronger predictor of mortality for older mexican americans than cognitive impairment.