Risk of death among persons with Alzheimer's disease: a national register-based nested case-control study.

Few studies have reported the risk of death related to Alzheimer's disease (AD) in large population-based cohorts. The objective of this study was to analyze the impact of AD on all-cause mortality in a nationwide sample of persons with AD. Community-dwelling persons with AD and an equal number of individually matched (age, gender, and region of residence) control persons without AD were identified from the registers of Social Insurance Institution of Finland at the end of 2005. Deaths in this sample (n = 56,041, mean age 79.7 years, 67.8% women) during a 57-month follow-up period were recorded. Using a nested case-control design, unadjusted and adjusted (cardiovascular disease, cancer, diabetes, and asthma and/or COPD) hazard ratios (HR) with 95% confidence intervals (CI) were computed using proportional hazards regression. The results were categorized according to age at death (<80, 80 to 89, ≥ 90 years) and duration of AD (≤ 3, 4 to 6, ≥ 7 years). The unadjusted HR for death associated with AD was 2.03 (95% CI: 1.97 to 2.09). The HR was highest in the youngest age category [HR = 3.46 (95% CI: 3.18 to 3.77)], and still significantly elevated in the oldest age category [HR = 1.50 (95% CI: 1.41 to 1.60)]. Comorbidity adjustments did not change the HRs, and even a short duration of AD (≤ 3 years) was associated with a significantly increased risk of death. In conclusion, AD was associated with an increased risk of death that was more pronounced at younger ages and existed even after a recent diagnosis of AD.