Background: Iron administration has been implicated as a cause of poor clinical outcome in maintenance hemodialysis (MHD) patients. However, the role of low iron levels in the clinical outcome of MHD patients is not clear.
Methods: We examined the predicting value of baseline serum iron level on prospective mortality and hospitalization in a cohort of all 1,283 MHD patients from 10 DaVita dialysis facilities in Los Angeles County, CA.
Results: Patients aged 57.8 +/- 15.2 years included 49% men, 45% Hispanics, 25% African Americans, and 53% patients with diabetes. During the first 3 months of the cohort, 97% of patients were administered erythropoietin (EPO) and 60% were administered intravenous iron (gluconate and/or dextran) at least once. During a 12-month follow-up, mortality was significantly greater (23%) in the lowest serum iron quartile (<45.3 microg/dL [<8.1 micromol/L]) compared with other quartiles (10% to 12%). Multivariate Poisson and Cox models adjusted for demographic features, dialysis dose and vintage, serum albumin and ferritin and blood hemoglobin concentrations, and administered EPO and iron doses showed that both serum iron level and iron saturation ratio had significant, but inverse, associations with prospective mortality and hospitalization. There was a statistically significant trend toward greater rates of mortality and hospitalization with lower serum iron levels. This reverse association remained significant in a subcohort of 322 MHD patients after additional adjustments for comorbid conditions and serum C-reactive protein level to reflect inflammation.
Conclusion: Low baseline serum iron indicators are associated with increased mortality and hospitalization in MHD patients independent of hemoglobin level, EPO and iron doses, indicators of nutrition and inflammation, and comorbid conditions. Clinical trials to examine the role of iron administration in improving morbidity and mortality by increasing serum iron levels in MHD patients are required.