**Background:** China faces a rapidly aging population, with 18.7% over 60 years old, and a rising burden of noncommunicable diseases (NCDs). Healthcare spending increased nearly 10.47-fold from 2000 to 2017. Chronic diseases account for a large share of medical costs among older adults, but precise estimates of attributable costs for specific conditions are lacking. This study aimed to quantify the impact of six prevalent chronic diseases on health care utilization and costs in Chinese seniors.
**Methods:** Data came from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), an ongoing cohort of adults aged 65+ in 23 provinces. The study analyzed 18,349 observations from the 2011, 2014, and 2018 waves. Six chronic diseases with the highest prevalence were selected: hypertension, arthritis, heart disease, cataracts, chronic lung disease (bronchitis/emphysema/asthma/pneumonia), and stroke or cerebrovascular disease (CVD). Health care costs (outpatient, inpatient, total) were self-reported and adjusted to 2018 CNY. A two-part random effects model was used: Part 1 (Logit) estimated the odds of any health care utilization; Part 2 (GLS) estimated log-transformed costs among users. The chronic disease attributable fraction (CDAF) was calculated by comparing predicted actual costs with counterfactual costs assuming no disease. Covariates included age, gender, residence, education, marital status, health insurance, comorbidity, smoking, drinking, BMI, ADL score, and income.
**Key Results:** In 2018, prevalence was: hypertension 41.20%, heart disease 16.59%, cataracts 13.88%, arthritis 13.31%, stroke/CVD 10.70%, chronic lung disease 10.54%. All six diseases significantly increased total health care utilization (ORs: hypertension 1.595, arthritis 1.487, heart disease 2.254, cataracts 1.173, chronic lung disease 2.174, stroke/CVD 1.816; all p<0.01). Among users, hypertension (β=0.105, p<0.01), heart disease (β=0.644, p<0.01), chronic lung disease (β=0.429, p<0.01), and stroke/CVD (β=0.562, p<0.01) were associated with higher total costs; arthritis and cataracts were not significant. The total CDAF for all six diseases was 45.05%. By disease: heart disease CDAF=22.11% (386.456 CNY per capita), stroke/CVD CDAF=13.24% (231.498 CNY), chronic lung disease CDAF=10.56% (184.544 CNY), hypertension CDAF=7.63% (133.458 CNY). For outpatient costs, CDAF was 36.00% overall; heart disease had the highest outpatient CDAF (15.92%). For inpatient costs, CDAF was 55.92% overall; heart disease had the highest inpatient CDAF (29.11%). Heterogeneity analysis showed higher attributable costs in males, urban residents, and those with higher education.
**Clinical Implications:** Chronic diseases impose a substantial economic burden on older Chinese adults, with heart disease, stroke, and chronic lung disease being the largest drivers. The majority of costs for stroke and chronic lung disease were inpatient, suggesting acute exacerbations are key cost drivers. Hypertension contributed mainly to outpatient costs. These findings support targeted interventions: improving hypertension control, preventing acute exacerbations of heart disease and stroke, and enhancing disease self-management. The higher attributable costs in urban and higher-educated groups may reflect better access to care. Policymakers should consider adjusting reimbursement policies and strengthening primary care and community-based chronic disease management to reduce the economic burden.