Reporting of clinically diagnosed dementia on death certificates: retrospective cohort study

Background: mortality statistics are a frequently used source of information on deaths in dementia but are limited by concerns over accuracy. Objective: to investigate the frequency with which clinically diagnosed dementia is recorded on death certificates, including predictive factors. Methods: a retrospective cohort study assembled using a large mental healthcare database in South London, linked to Office for National Statistics mortality data. People with a clinical diagnosis of dementia, aged 65 or older, who died between 2006 and 2013 were included. The main outcome was death certificate recording of dementia. Results: in total, 7,115 people were identified. Dementia was recorded on 3,815 (53.6%) death certificates. Frequency of dementia recording increased from 39.9% (2006) to 63.0% (2013) (odds ratio (OR) per year increment 1.11, 95% CI 1.07-1.15). Recording of dementia was more likely if people were older (OR per year increment 1.02, 95% CI 1.01-1.03), and for those who died in care homes (OR 1.89, 95% CI 1.50-2.40) or hospitals (OR 1.14, 95% CI 1.03-1.46) compared with home, and less likely for people with less severe cognitive impairment (OR 0.95, 95% CI 0.94-0.96), and if the diagnosis was Lewy body (OR 0.30, 95% CI 0.15-0.62) or vascular dementia (OR 0.79, 95% CI 0.68-0.93) compared with Alzheimer's disease. Conclusions: changes in certification practices may have contributed to the rise in recorded prevalence of dementia from mortality data. However, mortality data still considerably underestimate the population burden of dementia. Potential biases affecting recording of dementia need to be taken into account when interpreting mortality data.