Association of Social Isolation, Loneliness, with Incidence Risk of Cardiovascular Diseases: a Prospective Chinese Study

Background Cardiovascular diseases (CVD) are a leading cause of death both in China and worldwide. Social isolation and loneliness are closely associated with cardiovascular health. However, current research has mainly focused on European populations, and the findings are inconsistent. In China, evidence simultaneously examining the impact of social isolation and loneliness on the risk of incident CVD remains limited. Objective To investigate the independent and joint associations of social isolation and loneliness with the risk of CVD among middle-aged and older Chinese populations. Methods This prospective study, initiated in August 2024, included 10 668 participants from the China Health and Retirement Longitudinal Study who were free of heart disease and stroke at baseline. Social isolation and loneliness were assessed using baseline questionnaires. Incident CVD events were identified based on follow-up survey data. Cox proportional hazards regression models were used to estimate the associations between social isolation, loneliness, and CVD risk. Results During a median follow-up of 8.9 years, 2 409 (22.58%) participants developed CVD, including 1 777 cases (16.66%) of heart disease and 896 cases (8.40%) of stroke. The Cox proportional hazards regression analysis showed that, after adjustment for multiple confounders, compared to non-lonely individuals, lonely individuals had a 24% increased risk of CVD (HR=1.24, 95%CI=1.13-1.35), a 24% increased risk of heart disease (HR=1.24, 95%CI=1.12-1.38), and a 26% increased risk of stroke (HR=1.26, 95%CI=1.09-1.45). Compared to non-socially isolated individuals, socially isolated individuals had a 16% increased risk of stroke (HR=1.16, 95%CI=1.01-1.33), but show no significant association was found between social isolation and the risk of CVD or heart disease (P>0.05). No significant interaction was observed between social isolation, loneliness, and the risk of CVD or its subtypes (P>0.05). Participants who experienced both social isolation and loneliness had the highest risk of CVD (HR=1.23, 95%CI=1.09-1.39), particularly for stroke (HR=1.49, 95%CI=1.23-1.80). Conclusion Subjectively perceived loneliness is an independent risk factor for the incidence of CVD and its subtypes, with the highest risk observed when loneliness coexists with objectively assessed social isolation. The findings of this study suggest that encouraging middle-aged and older adults to maintain active social connections and alleviate feelings of loneliness play an important role in promoting cardiovascular health.