Under reporting of dementia deaths on death certificates using data from a population-based study (NEDICES)

Previous studies have shown that dementia is frequently omitted as a cause of death from the death certificate in patients with long-standing dementia. However, most studies exclude those undiagnosed dementia sufferers in the population. In order to overcome this problem, it is necessary to examine all the participants or to screen the population for symptoms of dementia and confirm the diagnosis with a clinical examination (two-phase approach). We used this latter methodology to estimate the proportion of reporting of dementia on death certificates in a prospective population-based study (NEDICES), involving 4,197 elderly people. Community-dwelling subjects with and without dementia were identified and followed during a median of 12.5 years, after which the death certificates of those who deceased were examined. A total of 1,976 (47.1%) died (403 subjects with dementia). Dementia was rarely reported as the primary cause of death, even in known cases of dementia (20.8%). Indeed it was reported in only 13.3% of those with mild dementia and 24.3% of those with moderate or severe dementia; in 24.9% of those with possible or probable Alzheimer's disease; and in 11.9% of those with non-Alzheimer dementia. In a stepwise multiple logistic regression analysis with the dependent variable being presence or absence of dementia on the death certificate, the significant associated independent variables were age at death, severity of dementia, and etiology of dementia. We conclude that reporting of dementia on death certificates remains poor. This suggests a lack of awareness of the importance of dementia as a cause of death.