Predictors of mortality in patients with Alzheimer's disease living in nursing homes

Abstract

Objectives: To identify factors associated with mortality in patients with Alzheimer's disease, and to evaluate whether these factors vary according to severity of cognitive impairment.

Methods: Data were from the SAGE database which includes information on all residents admitted between 1992 and 1995 to all Medicare/ Medicaid certified nursing homes of five US states. We conducted a longitudinal follow up study (median 23 months) on 9264 patients aged 65 years and above with a diagnosis of Alzheimer's disease. Patient data including demographic characteristics, dementia severity, comorbidity, and other clinical and treatment variables were collected with the Minimum Data Set. Information on death was derived through linkage to Medicare files. Baseline characteristics were used to predict survival in univariate and multivariate Cox proportional hazard models.

Results: Overall mortality rate was 50%, with a first year rate of 25.7%. Increased age (risk ratio (RR) 1. 83; 95% confidence interval (95% CI) 1.65-2.03, for patients 85+ years), male sex (RR 1.81; 95% CI 1.70-1.94), limitation in physical function (RR 1.45; 95% CI 1.27-1.66), a condition of malnutrition (RR 1.31; 95%CI 1.23-1.39), the presence of pressure ulcers (RR 1.24; 95% CI 1.13-1.36), a diagnosis of diabetes mellitus (RR 1.32; 95% CI 1.21-1.43), and of cardiovascular diseases (RR 1.22; 95% CI 1. 14-1.30) were independent predictors of death, regardless of the severity of baseline dementia. Sensory problems (hearing and vision) and urinary incontinence were associated with increased mortality only among patients with less severe dementia. The presence of disruptive behaviour, aphasia, and a diagnosis of Parkinson's disease were not related to survival. African-Americans and other minority groups were less likely to die relative to white people.

Conclusions: Age, sex, functional limitation, and malnutrition seem to be the strongest predictors of death for patients with Alzheimer's disease in nursing homes. Altogether, severity of dementia has no influence on survival, yet the predictive role of certain variables depends on the degree of impairment. Minority groups have a reduced risk of death relative to white people.