Change in social isolation and risk of frailty among older adults: results from two prospective cohorts

OBJECTIVE: This study investigates the longitudinal association between changes in social isolation and incident frailty in older adults. METHODS: Older adults from the China Health and Retirement Longitudinal Study (CHARLS) and the Survey of Health, Ageing, and Retirement in Europe (SHARE). About 3931 participants from CHARLS and 15,817 participants from SHARE aged 60 years and older who were non-frail at baseline were included. Social isolation was assessed using six questions in CHARLS (score ≥ 3) and four questions in SHARE (score ≥ 2). Frailty was defined as Rockwood Frailty Index ≥25. Changes in social isolation were categorized as "no isolation," "developed isolation," "resolved isolation," and "persistent isolation". RESULTS: In CHARLS, persistent isolation was associated with an increased risk of frailty (hazard ratio [HR], 1.2; 95 % confidence interval [95 % CI], 1.1-1.4), while neither developed isolation (HR, 1.1; 95 % CI, 1.0-1.3) nor resolved isolation (HR, 1.1; 95 % CI, 0.9-1.2) showed significant associations. In SHARE, both persistent isolation (HR, 1.4; 95 % CI, 1.2-1.6) and resolved isolation (HR, 1.3; 95 % CI, 1.0-1.6) were significantly associated with frailty, whereas developed isolation showed no significant association (HR, 1.1; 95 % CI, 1.0-1.2). CONCLUSIONS: Changes in social isolation are significantly associated with the incidence of frailty in older adults.