Gender differences in the relation between comorbidity and mortality of patients with Alzheimer’s disease

OBJECTIVE: To investigate whether differences in the number and type of comorbid conditions may help explain the gender gap in mortality among patients with AD. BACKGROUND: The prevalence and incidence of AD are higher among women, who also have more severe cognitive impairment and accelerated decline. However, men have an exceedingly higher mortality. METHODS: The authors conducted a retrospective cohort study on 5,831 men and 17,918 women with a diagnosis of AD. Data were from the Systematic Assessment of Geriatric drug use via Epidemiology (SAGE) database, which includes information on residents of 1,492 nursing homes in five US states (1992-1995). Men and women were compared with respect to demographic characteristics, dementia severity, psychiatric and behavioral symptoms, indicators of physical disability, and general health status. Also compared were age- and race-adjusted prevalence of all comorbid conditions at each level of cognitive impairment. In survival analyses, the risk of death and of hospitalization were determined by gender and level of cognitive impairment. Finally, gender-related differences in the intensity of pharmacologic treatment were examined. RESULTS: Women were older than men (83+/-7 versus 81+/-7 years) and were more likely to exhibit severe cognitive deterioration (27% versus 19% among men). Overall, there were no significant gender-related differences on several measures of physical disability (activities of daily living performance, gait and history of falls, incontinence, pressure sores), but significantly more women were underweight (45% versus 37% among men). However, the age- and race-adjusted 1-year mortality rate was 17% for women and 31% for men. The mortality rate of women at the highest degree of dementia severity was lower than the rate for men with minimal cognitive impairment. At any level of cognitive impairment, the prevalence of arrhythmia, chronic obstructive pulmonary disease, PD, and cancer was higher among men. Women were also less likely to be hospitalized, and they received fewer medications for each given disease. CONCLUSIONS: The survival advantage of women with AD relative to men may occur as a result of fewer comorbid clinical conditions associated with the diagnosis of dementia.