Social Asymmetry and Risk of Morbidity and Mortality.

Importance: Social asymmetry refers to the discrepancy between subjective loneliness and objective social connections. Although both loneliness and isolation have been linked with risk of premature mortality and morbidity, the association between the 2 is poorly understood. Objective: To explore the associations between social asymmetry and risk of incident morbidity and mortality in a national population cohort. Design, Setting, and Participants: Prospective cohort study using data from wave 4 (2008-2009) of the English Longitudinal Study of Aging (ELSA) as baseline. Participants were aged 50 years and older living in England. Data were analyzed from April to August 2025. Exposures: Social asymmetry was quantified as the residual score from regressing scaled loneliness on scaled social isolation. Main Outcomes and Measures: Incident cardiovascular disease (CVD), chronic obstructive pulmonary disease (COPD), dementia, and all-cause mortality, through data linkage to hospital episode statistics and mortality registry data up to 2024. Results: Of 7845 participants (mean [SD] age at baseline, 65.5 [9.5] years; 4283 [54.6%] women; 7694 [98.1%] White and 151 [1.9%] other race or ethnicity) with a mean (SD) follow-up period of 13.6 (4.2) years, 2775 deaths and 2415 CVD, 989 COPD, and 710 dementia cases were recorded. Higher social asymmetry (higher loneliness than estimated by isolation) was associated with increased risk of CVD (hazard ratio [HR], 1.06; 95% CI, 1.02-1.10) and all-cause mortality (HR, 1.04; 95% CI, 1.01-1.06). Compared with those in the socially resilient group, those in the socially vulnerable group had a higher risk of all-cause mortality (HR, 1.13; 95% CI, 1.04-1.22), CVD (HR, 1.16; 95% CI, 1.04-1.30), and COPD (HR, 1.21; 95% CI, 1.04-1.42). Compared with the concordant low lonely group (low loneliness, low isolation), participants in the concordant high lonely group (high loneliness, high isolation) had an increased risk for all health outcomes investigated, while those in the discordant susceptible category (high loneliness, low isolation) had an increased risk for CVD and mortality; the discordant robust group (low loneliness, high isolation) had no association for any outcomes except for dementia. Conclusions and Relevance: In this cohort study, higher social asymmetry was associated with increased risk of incident morbidity and mortality, emphasizing the importance of evaluating both loneliness and isolation in studies of health outcomes. Future interventions could leverage this novel measurement to identify high-risk groups to target.