Abstract
BACKGROUND: Metabolic syndrome (MetS) presents significant challenges to public health, yet prospective evidence on the associations of social isolation and loneliness with mortality in this population remains limited.
METHODS: We analyzed 347,864 participants from the UK Biobank, including 101,276 with MetS. Social isolation and loneliness were assessed using self-reported questionnaires. Among individuals with MetS, Cox proportional hazards models were used to examine their associations with all-cause, cardiovascular disease (CVD), and cancer mortality. Joint associations of social isolation and loneliness were also examined, and multiple sensitivity analyses were conducted.
RESULTS: During a median follow-up of 12.48 years, 12,664 deaths occurred among participants with MetS. Social isolation was associated with higher risks of all-cause, CVD, and cancer mortality; for index ≥2 versus 0, hazard ratios (HRs) and 95% confidence intervals (CIs) were 1.29 (1.23-1.36), 1.39 (1.26-1.53), and 1.18 (1.10-1.28), respectively. Loneliness was associated with higher risks of all-cause and CVD mortality, with HRs (95% CIs) of 1.16 (1.09-1.25) and 1.32 (1.15-1.50) for index 2 versus 0, but not cancer mortality. Co-occurring higher social isolation and loneliness was associated with the highest mortality risk. Findings were robust in sensitivity analyses.
CONCLUSIONS: Social isolation and loneliness were associated with increased risks of all-cause and CVD mortality among individuals with MetS, with social isolation also associated with cancer mortality. Mortality risk was highest among individuals with coexisting social isolation and loneliness.