Frailty in relation to metabolic syndrome: Cross-sectional and longitudinal insights from the CHARLS and ELSA cohorts

BACKGROUND: With global population ageing, frailty poses a major threat to healthy independence in the elderly. However, whether metabolic syndrome (MetS) increases the risk of frailty is still unclear. This study investigated this association in two prospective cohorts. METHODS: Data were obtained from the China Health and Retirement Longitudinal Study (CHARLS) and the English Longitudinal Study of Ageing (ELSA). Logistic and linear regression were utilized in cross-sectional analyses to assess associations between MetS and frailty and the frailty index (FI), respectively. Cox models were employed in longitudinal analyses to evaluate whether baseline MetS predicted the development of frailty during follow-up among participants who were non-frail at study entry. Additionally, Kaplan-Meier (KM) survival analysis was performed to assess cumulative frailty incidence across different MetS status groups. RESULTS: A total of 14,604 participants were included at baseline (CHARLS: 8425; ELSA: 6179), with 10,763 followed longitudinally (CHARLS: 5647; ELSA: 5116). After multivariable adjustment, MetS was significantly associated with increased frailty prevalence (CHARLS: OR = 1.45, 95%CI 1.26-1.66; ELSA: OR = 1.49, 1.27-1.75) and higher FI (CHARLS: β = 0.020, 0.015-0.024; ELSA: β = 0.026, 0.019-0.033). Longitudinally, MetS predicted elevated frailty risk (CHARLS: HR = 1.28, 1.16-1.42; ELSA: HR = 1.20, 1.06-1.36). KM survival analysis revealed that participants with MetS had a significantly higher cumulative incidence of frailty in both cohorts. CONCLUSIONS: Our findings suggest that MetS may play a significant role in the development and progression of frailty. Accordingly, targeting MetS could be a viable approach for preventing or delaying the onset of frailty in older adults.