Time-effect of depression on chronic disease and related medical expenditures in middle-aged and older adults in China

Depressive symptoms are increasingly recognized as a potential risk factor for adverse physical health outcomes, yet longitudinal evidence from community‑based middle‑aged and older populations remains limited. This study aimed to prospectively examine the association of depressive symptoms with incident chronic diseases, multimorbidity, and outpatient expenditures among Chinese adults aged 45 years and older. We analysed data from 4,872 participants free of any chronic disease at baseline (mean age 57.4 years; 49.2% male) enrolled in the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2020, with depressive symptoms assessed using the 10‑item Depression self-rating scale (CES‑D). Generalized estimating equation models were employed to estimate the longitudinal associations, with sequential adjustments for demographic characteristics, socioeconomic status, and lifestyle factors (smoking and drinking history). After a median follow‑up of nine years, baseline depressive symptoms were significantly associated with an increased risk of overall incident chronic disease (OR = 1.26, 95% CI: 1.14–1.39), with a graded relationship by the number of conditions, particularly for multimorbidity. Specifically, depression independently predicted higher risks of incident digestive diseases (1.61, 1.32–1.96), arthritis or rheumatism (1.43, 1.22–1.68), and chronic respiratory diseases (1.40, 1.08–1.82). In addition, participants with depressive symptoms incurred significantly greater outpatient expenditures over the follow‑up period compared with their non‑depressed counterparts. Our findings indicate that depressive symptoms independently increase the risk of chronic disease onset, especially multimorbidity and specific disease types, as well as the burden of healthcare costs, underscoring the importance of integrating mental health screening into primary care and chronic disease prevention strategies for community‑dwelling middle‑aged and older adults, including those with subclinical depressive symptoms who have not received a formal psychiatric diagnosis.