Abstract
OBJECTIVE: To examine the association of changes in loneliness with subsequent cardiometabolic comorbidity (CMM) among middle-aged and older Chinese and South Korean adults. METHODS: We used the harmonized individual-level data from the China Health and Retirement Longitudinal Study (CHARLS, n = 9381) from China and the Korean Longitudinal Study of Aging (KLoSA, n = 5052) from South Korea. In both CHARLS and KLoSA, loneliness was measured using a single item from the 10-item Center for Epidemiological Studies Depression Scale (CESD-10) at baseline and in the second survey. CMM was defined as the presence of two or more cardiometabolic conditions, including diabetes, heart disease, and stroke, based on physician-diagnosed self-report. Within each cohort, we used the multivariable Cox proportional hazards models to estimate adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) of incident CMM according to changes in loneliness (never, initiated, relieved, and persistent) over 7 years (CHARLS) or 6 years (KLoSA) of follow-up. RESULTS: In CHARLS, initiated (aHR 1.42, 95%CI 1.14-1.78), relieved (aHR 1.40, 95%CI 1.16-1.70), and persistent (aHR 2.03, 95%CI 1.64-2.51) loneliness were associated with an increased likelihood of experiencing CMM. In KLoSA, both relieved (aHR 1.72, 95%CI 1.07-2.76) and persistent (aHR 1.86, 95%CI 1.21-2.88) loneliness were significantly associated with CMM, whereas the initiated loneliness showed no significant association (aHR 1.25, 95%CI 0.76-2.07). CONCLUSIONS: Changes in loneliness were associated with an increased risk of subsequent CMM in both China and South Korea, with the strongest associations observed among individuals experiencing persistent loneliness. These findings indicate that loneliness is a dynamic and potentially modifiable risk factor for cardiometabolic multimorbidity across different sociocultural contexts. Early identification and targeted interventions addressing loneliness may contribute to the prevention of CMM among middle-aged and older adults.