The relationship of initial transferrin saturation to cardiovascular parameters and outcomes in patients initiating dialysis

Background: The prognostic importance of anemia for cardiovascular (CV) events and mortality has been extensively investigated. However, little is known about the impact of transferrin saturation (TSAT), a marker reflecting the availability of iron for erythropoiesis, on clinical outcome in dialysis patients. Methods: A total of 879 anemic incident dialysis patients were recruited from the Clinical Research Center for End-Stage Renal Disease in Korea and were divided into 3 groups according to baseline TSAT of ≤20%, 20-40%, and ≤40%. Results: There were no differences in hemoglobin levels and the proportion of patients on erythropoiesis-stimulating agents or iron supplements among the 3 groups. During a mean follow-up duration of 19.3 months, 51 (5.8%) patients died. CV composite (11.71 vs. 5.55 events/100 patient-years, P = 0.001) and all-cause mortality rates (5.38 vs. 2.31 events/100 patient-years, P = 0.016) were significantly higher in patients with TSAT ≤20% compared to those with TSAT 20-40% (reference group). Cox regression analysis revealed that patients with TSAT ≤20% had 1.62- and 2.19-fold higher risks for CV composite outcome (P = 0.046) and all-cause mortality (P = 0.030). Moreover, TSAT ≤20% was significantly associated with left ventricular hypertrophy [odds ratio (OR) = 1.46], high-sensitivity C-reactive protein ≥3 mg/dL (OR = 2.09), N-terminal pro B-type natriuretic peptide ≥10000 pg/mL (OR = 2.04), and troponin-T≥0.1 ng/mL (OR = 2.02), on logistic regression analysis. Conclusions: Low TSAT was a significant independent risk factor for adverse clinical outcome in incident dialysis patients with anemia, which may be partly attributed to cardiac dysfunction and inflammation.