Age-Standardized Comorbidity Prevalence of Cardiometabolic Conditions and Socioeconomic Inequalities in Hong Kong: A District Comparison

Background: Hypertension (HTN) and Type 2 diabetes mellitus (T2DM) are leading drivers of the global cardiometabolic disease burden and major contributors to preventable morbidity and mortality. In Hong Kong, where population ageing and lifestyle-related risk factors are increasingly prevalent, both conditions and their complications pose substantial challenges to the healthcare system. Although territory-wide prevalence figures are available, small area district-level evidence on the burden of these diseases and their associated complications remains limited. Disparities are likely due to heterogeneity in demographic composition, socioeconomic status, and primary care accessibility across Hong Kong's eighteen administrative districts. There is also a lack of accessible, age-adjusted, district-level disease visualization in Hong Kong. Objectives: This study estimates the age-standardized prevalence rates (ASPR) of HTN, T2DM, and their associated complications across the eighteen districts of Hong Kong, formally evaluate the statistical significance of inter-district disparities, and rank the districts according to disease burden to inform place-based health planning. Methods: This study analyzed the prevalence of chronic diseases from 2014 to 2023 in 18 districts among an adult cohort aged equal or above 35 years using data collected from the Hong Kong Hospital Authority (HA) electronic health records, using the International Classification of Diseases, Ninth Revision (ICD-9) diagnostic codes, the International Classification of Primary Care (ICPC) codes, and the disease flags to identify diseases. Sample weights are used to reflect the total population. HTN, T2DM, and their major complications were identified according to standardized diagnostic criteria. ASPR were calculated for each district with the WHO World Standard Population as the standard. Inter-district disparities in disease prevalence were assessed using Cochran's Q test, with statistical significance set at P <0.05. The slope index of inequality (SII) was also used to analyze the socioeconomic inequality between districts. Districts were subsequently ranked according to their ASPR for each condition to identify high-burden and low-burden areas. Results: 1,756,521 patients (52.71% females) contribute 9,906,729 patient-years from 2014 to 2023. Substantial inter-district variation and increasing trend were observed in the ASPR of HTN, T2DM, and their complications. The weighted ASPR of HTN varied by 27.3% from 46,701 (95% CI: 45,691-47,711) per 100,000 population in Tsuen Wan district to 59,445 (95% CI: 58,759-60,130) per 100,000 population in Yuen Long district, and the weighted ASPR of T2DM ranged from 20,464 (Tsuen Wan, 95% CI: 19,803-21,124) per 100,000 population to 28,275 (Yuen Long, 95% CI: 27,792-28,758) per 100,000 population across the districts in 2023. All diseases showed district disparities (all P <0.05). Cochran's Q test demonstrated statistically significant disparities across districts and showed no convergence through the period. The SII test also showed the most serious inequality exists in HTN, with the lower socioeconomic position districts have more burden. Conclusion: Significant geographic disparities exist in the prevalence of HTN, T2DM, and their complications across Hong Kong's eighteen districts. These findings highlight the need for district-specific public health strategies, equitable allocation of primary care resources, and targeted chronic disease prevention and management programs in high-burden areas.