Associations of intrinsic capacity and social isolation with cardiometabolic diseases: A prospective multi-cohort study

BACKGROUND: Cardiometabolic disease (CMD) is a widespread public health concern. Few studies have investigated the association of intrinsic capacity (IC) with a range of specific CMD outcomes from an international perspective. We examined the association between IC and CMD along with the joint effect of social isolation. METHODS: This prospective, multi-regional cohort study integrated individual-level data from three studies conducted between 2006 and 2020: the Chinese Health and Retirement Longitudinal Study (CHARLS); the English Longitudinal Study of Aging (ELSA); and the Korean Longitudinal Study of Aging (KLoSA). Individuals aged 45 years or more without CMD at baseline and with complete follow-up were included. Cox proportional hazards models were used to assess the IC-CMD association. Whether social isolation modified the IC-CMD association was also investigated. RESULTS: In total, 12,792 participants were included. During a median follow-up of 7 years, 4735 participants developed CMD. After adjusting for confounders, "impaired" IC participants (CHARLS: hazard ratio [HR] 1.25, 95% confidence interval [CI] 1.12-1.39) and "pre-impaired" IC participants (ELSA: HR 1.26, 95% CI 1.08-1.46) had significantly elevated risks of incident CMD than "robust" participants. These relationships were most significant for stroke (CHARLS: HR 1.78, 95% CI 1.28-2.46; KLoSA: HR 1.51, 95% CI 1.05-2.19; ELSA: HR 2.23, 95% CI 1.22-4.09; pooled: HR 1.85, 95% CI 1.48-2.32; I² = 0.0%, p = 0.740). Compared with participants with robust IC and social non-isolation, those with impaired IC and social isolation had a higher risk of CMD (CHARLS: HR 1.37, 95% CI 1.08-1.73; pooled: HR 1.34, 95% CI 1.13-1.59; I² = 49.6%, p = 0.132), especially diabetes (pooled HR 1.91, 95% CI 1.37-2.66; I² = 0.0%, p = 0.531). CONCLUSION: Impaired IC was associated with an increased risk of CMD. The strength of this association varied with the CMD subtypes and across countries. Moreover, IC and social isolation exhibited a joint effect in this relationship.