Trends in Dementia Incidence, Prevalence, and Mortality among Older Hong Kong Chinese, 2005-2019: A Population-Based...

While many Western countries have reported a declining trend in dementia incidence, epidemiological data on the dementia burden in Chinese populations remain scarce. We aimed to examine the trends in the incidence, prevalence, and mortality of dementia in the older Hong Kong Chinese population from 2005 to 2019.

Using the territory-wide electronic health record database, we identified all public healthcare service users aged ≥60 years in Hong Kong between 2005 and 2019. The annual incidence and prevalence of dementia were estimated, and time trends were analyzed using joinpoint regression. We matched each dementia case with up to 10 dementia-free controls and compared their 1-year and 5-year mortality risk across the study period using Cox models, adjusted for age, sex, and comorbidities.

Among 2,224,854 individuals, 151,511 developed incident dementia during the study period. Age-standardized incidence per 1,000 person-years increased from 7.4 in 2005 to 9.4 in 2010 (annual percent change [APC]: 5.5%; 95% CI: 2.6-10.8) but subsequently declined to 6.3 in 2019 (APC: -3.6%; 95% CI: -5.1 to -2.5), with the most pronounced decrease observed in the oldest-old adults aged ≥80 years. The overall prevalence of dementia increased from 3.9% in 2005 to 4.8% in 2019. Individuals with dementia had significantly higher 1-year (hazard ratio [HR]: 2.92; 95% CI: 2.88-2.96) and 5-year (HR: 2.07; 2.06-2.09) mortality risks; these associations remained consistent throughout the study period.

Dementia incidence has declined substantially after 2010 among older Hong Kong Chinese, particularly in the oldest-old adults. However, dementia prevalence remains high and is strongly associated with increased mortality risk, highlighting the need for continued public health efforts to address its burden.