Is the Rise in Reported Dementia Mortality Real? Analysis of Multiple Cause of Death Data for Australia and the United States

Official statistics in Australia and the United States report large recent increases in dementia mortality rates. This study assesses whether these trends are biased by an increasing tendency of medical certifiers (predominantly physicians) to report on the death certificate that dementia was a direct cause of death. Regression models of multiple cause of death data in Australia (2006-16) and the US (2006-17) were constructed to adjust dementia mortality rates for changes in death certification practices. Compared with official statistics, the recent increase in adjusted age-standardized dementia death rates was less than half as large in Australia and about two-thirds as large in the US. Further adjustment for changes in reporting of dementia anywhere on the death certificate implied even lower dementia mortality increases. Declines in reporting of cardiovascular diseases as co-morbid conditions also contributed to dementia mortality rate rises. The increasing likelihood of dementia reported as directly leading to death largely explains recent increases in dementia mortality rates in both countries. However, studies find that reported dementia on death certificates remains low compared to clinical evaluations of its prevalence. Improved guidance and training for certifiers in reporting dementia on death certificates will help standardize mortality statistics within and between countries.