Social isolation and risk of mortality in middle-aged and older adults with arthritis: a prospective cohort study of four cohorts

Social isolation is common and associated with many adverse outcomes. The evidence regarding social isolation and mortality among middle-aged and older adults with arthritis was lacking. The study aimed to examine the association between social isolation and mortality in this population. This study used data from four prospective cohorts: National Health and Aging Trends Study (NHATS), English Longitudinal Study of Ageing (ELSA), China Health and Retirement Longitudinal Study (CHARLS), and Chinese Longitudinal Healthy Longevity Survey (CLHLS). Individuals with arthritis (including osteoarthritis and rheumatoid arthritis) in these cohorts were included. Social isolation was assessed using self-reported questionnaires. Cox proportional hazards regression models were conducted to evaluate these associations. At baseline, a total of 16,035 individuals with arthritis (3872 from NHATS, 3259 from ELSA, 5645 CHARLS, and 3259 from CLHLS) were included. Social isolation was associated with increased risk of mortality in meta-analysis (hazard ratio [HR] 1.42, 95% confidence interval [CI]: 1.26-1.59), and individual cohorts (NHATS: HR 1.53, 95% CI 1.19-1.97; ELSA: HR 1.31, 95% CI 1.02-1.67; CLHLS: HR 1.50, 95% CI 1.36-1.64) after being adjusted for confounder factors. Additionally, with increasing social isolation score, the risk of mortality also increased in meta-analysis (HR 1.19, 95% CI 1.15-1.24), as well as in individual cohorts (NHATS: HR 1.22, 95% CI 1.14-1.30; CLHLS: HR 1.19, 95% CI 1.13-1.26). Subgroups analysis results suggested that social isolation was independently associated with a higher likelihood of mortality in middle-aged and older adults with arthritis, regardless of gender, lifestyles, and chronic diseases.