Co-occurring patterns of social isolation and loneliness and their associations with cardiovascular disease risk among middle-aged and older adults: a group-based dual-trajectory modeling study

Social isolation and loneliness are distinct but related psychosocial factors that may be jointly associated with health outcomes. We aimed to identify co-occurring longitudinal patterns of social isolation and loneliness and to examine their associations with cardiovascular disease (CVD) risk among middle-aged and older adults. This study included 10,823 adults aged 45 years and older from the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2020. Group-based dual trajectory modeling was used to identify co-occurring patterns of social isolation and loneliness. Discrete-time proportional hazards models were used to examine the associations between these trajectory patterns and CVD risk. Five co-occurring patterns of social isolation and loneliness were identified among middle-aged and older adults over the nine-year follow-up. Compared with Pattern 2, characterized by moderate social isolation and low loneliness, the highest CVD risk was observed in Pattern 4, characterized by moderate social isolation and fluctuating loneliness (HR = 1.53, 95% CI: 1.36–1.72). Elevated CVD risks were also observed in Pattern 5, characterized by high social isolation and high loneliness (HR = 1.29, 95% CI: 1.10–1.49), and Pattern 1, characterized by low social isolation and low loneliness (HR = 1.16, 95% CI: 1.04–1.30). Pattern 3, characterized by high social isolation and low loneliness, did not differ significantly from Pattern 2 in CVD risk. These findings highlight the importance of considering the joint longitudinal patterns of objective social isolation and subjective loneliness when identifying middle-aged and older adults at elevated risk of CVD. Individuals with fluctuating or high loneliness, particularly in the context of moderate or high social isolation, may warrant closer cardiovascular risk assessment and connection to social or emotional support resources.