Social frailty and mortality risk in middle-aged and older adults: a prospective cohort study.

Social frailty is common and associated with several adverse outcomes in older adults. However, its prevalence and effects on mortality in younger populations and the underlying cause of mortality are poorly understood. To examine the association of social frailty with all-cause and cause-specific mortality in adults across a wide age spectrum, we used data from the UK Biobank, a prospective cohort included 421,644 individuals aged 37-73 years enrolled from 2006 to 2010. Social frailty status was assessed based on Bunt's concept (financial difficulty, live alone, less social activity and rarely contacts with friends/family). The prevalence of pre-social frailty and social frailty were 35.74% and 19.87%, respectively, indicating that more than half of the participants were at risk of cumulative depletion of essential social resources. Both pre-social frailty and social frailty were associated with higher risk of all-cause and cause-specific mortality (including malignant neoplasms, heart disease, cerebrovascular diseases, respiratory diseases, diabetes mellitus, and others caused) in adults across a wide age spectrum, independent of sociodemographic factors, lifestyles, chronic diseases, mental health, and physical frailty status. These findings indicate that social frailty, as a robust and multidimensional construct, effectively captures the risk of losing social resources. Thus, assessing and addressing social frailty can reduce mortality risk.