Anemia as an independent risk factor for sarcopenia in older adults: a cohort study based on CHARLS and ELSA

This study examined the prospective association between anemia and incident sarcopenia using two large-scale aging cohorts: the China Health and Retirement Longitudinal Study (CHARLS) and the English Longitudinal Study of Ageing (ELSA). This prospective, population-based cohort study included participants aged ≥ 45 years without sarcopenia at baseline from CHARLS (Wave 1, 2011) and ELSA (Wave 4, 2008-2009). Hazard ratios (HRs) were estimated using multivariable Cox proportional hazards models with sequential adjustment for demographic, socioeconomic, lifestyle, and health-related confounders. Subgroup analyses and sensitivity analyses were conducted to test robustness. After full adjustment, baseline anemia was significantly associated with an increased risk of incident sarcopenia in both CHARLS (n = 1,407; HR = 1.73, 95% CI: 1.07-2.79) and ELSA (n = 2,921; HR = 2.62, 95% CI: 1.50-4.56). In ELSA, a stronger association was observed among females (HR = 4.72, 95% CI: 2.25-9.93), with a marginal sex interaction (P for interaction = 0.054). No significant sex interaction was detected in CHARLS.Sensitivity analyses using sequential adjustment models confirmed consistent results (CHARLS: HR = 1.53, 95% CI: 1.17-2.01; ELSA: HR = 2.59, 95% CI: 1.30-5.18). This bicohort study suggests that baseline anemia is associated with a higher risk of developing sarcopenia in older adults from two distinct populations (Chinese and British). The strength of this association and the susceptible subgroups differed between cohorts. Further studies are needed to determine whether correcting anemia can reduce sarcopenia incidence and whether risk stratification based on anemia improves prevention strategies.