Supplementary Material for: Serum Ferritin Variations and Mortality in Incident Hemodialysis Patients
Background: Higher serum ferritin levels may be influenced by iron use and inflammation, and are associated with higher mortality in hemodialysis (HD) patients. We hypothesized that a major rise in serum ferritin is associated with a higher risk of mortality, irrespective of baseline serum ferritin in incident HD patients. Methods: In a cohort of 93,979 incident HD patients between 2007 and 2011, we examined the association of change in serum ferritin from the baseline patient quarter (first 91 days from dialysis start) to the subsequent quarter with mortality. Multivariable adjustments were done for case-mix and markers of the malnutrition, and inflammation complex and intravenous iron dose. Change in serum ferritin was stratified into 5 groups: <-400, -400 to <-100, -100 to <100, 100 to <400, and ≥400 ng/mL/quarter. Results: The median change in serum ferritin was 89 ng/mL/quarter (interquartile range -55 to 266 ng/mL/quarter). Compared to stable serum ferritin (-100 to <100 ng/mL/quarter), a major rise (≥400 ng/mL/quarter) was associated with higher all-cause mortality (hazard ratio [95% CI] 1.07 [0.99-1.15], 1.17 [1.09-1.24], 1.26 [1.12-1.41], and 1.49 [1.27-1.76] according to baseline serum ferritin: <200, 200 to <500, 500 to <800, and ≥800 ng/mL in adjusted models, respectively. The mortality risk associated with a rise in serum ferritin was robust, irrespective of intravenous iron use. Conclusions: During the first 6-months after HD initiation, a major rise in serum ferritin in those with a baseline ferritin ≥200 ng/mL and even a slight rise in serum ferritin in those with a baseline ferritin ≥800 ng/mL are associated with higher mortality.