Association Between Social Isolation and Risk of Hypertension Among the Middle-aged and Older: A Propensity Score–matched Cohort Study

Background: Social isolation has emerged as a growing public health concern and may be an underrecognized risk factor for hypertension. However, evidence on its longitudinal association with hypertension remains limited and inconsistent. Methods: The data of the national cohort study were collected from the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2020. A total of 3280 participants aged 45 years and older without hypertension at baseline were included. Propensity score matching (PSM) was applied to balance covariates between socially isolated and non-isolated groups. Cox proportional hazards models were used to estimate the association between social isolation and incident hypertension. Results: 14.57% of middle-aged and older adults in this study were classified as socially isolated. After matching, a total of 470 socially isolated individuals were successfully matched to 470 non-isolated counterparts. The Kaplan–Meier cumulative incidence curves demonstrated a consistently significant association between social isolation and the incidence of hypertension, both before and after PSM (p = 0.0093; p =0.0215). Subgroup analyses showed the association remained robust among individuals among the middle-aged, men, individuals with lower education levels, smokers, those without major chronic conditions, and those with medical insurance. No significant interactions were found across subgroups. Conclusion: This association persisted after PSM and adjustment for some key confounders, highlighting the role of social factors in shaping hypertension risk and warranting further investigation. Keywords: Social isolation, Hypertension, Propensity score matching, the Middle-aged and older