Supplementary Material for: Trends in dementia incidence, prevalence, and mortality among older Hong Kong Chinese, 2005–2019: a population-based study

Background: 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 trends in incidence, prevalence, and mortality of dementia in the older Hong Kong Chinese population from 2005 to 2019. Methods: 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. 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. Results: 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 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 mortality risks (HR: 2.07; 2.06–2.09); these associations remained consistent throughout the study period. Conclusions: Dementia incidence has declined substantially after 2010 among older Hong Kong Chinese, particularly in the oldest-old. 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.

背景：尽管诸多西方国家已报道痴呆发病率呈下降趋势，但针对中国人群痴呆负担的流行病学数据仍较为匮乏。本研究旨在分析2005年至2019年香港老年华人人群痴呆的发病率、患病率及死亡率变化趋势。
方法：本研究依托全港电子健康档案数据库，筛选出2005年至2019年间香港所有60岁及以上的公立医疗卫生服务使用者。我们估算了痴呆的年度发病率与患病率，并采用分段连接点回归（joinpoint regression）分析其时间变化趋势。此外，我们将每例痴呆病例与至多10名无痴呆的对照者进行匹配，在校正年龄、性别及合并症后，采用Cox模型（Cox model）比较研究期间两组受试者1年及5年的死亡风险。
结果：本研究共纳入2224854名受试者，其中151511例在研究期间新发痴呆。每1000人年的年龄标准化发病率从2005年的7.4升至2010年的9.4（年度变化百分比（annual percent change, APC）：5.5%；95%置信区间（confidence interval, CI）：2.6~10.8），随后降至2019年的6.3（APC：-3.6%；95%CI：-5.1~-2.5），其中80岁及以上的高龄老年人降幅最为显著。总体痴呆患病率从2005年的3.9%升至2019年的4.8%。痴呆患者的1年死亡风险（风险比（hazard ratio, HR）：2.92；95%CI：2.88~2.96）与5年死亡风险（HR：2.07；95%CI：2.06~2.09）均显著高于对照人群，且上述关联在整个研究期间保持一致。
结论：香港老年华人人群的痴呆发病率在2010年后已大幅下降，尤以高龄老年人为甚。但痴呆患病率仍处于较高水平，且与死亡风险升高密切相关，这凸显了持续开展公共卫生工作以应对痴呆负担的必要性。