Background: There is confounding data regarding the best method of iron supplementation in chronic kidney disease (CKD), without a consistent approach in clinical practice. Objectives: To evaluate the efficacy and safety of intravenous (IV) iron versus oral iron in patients treated for anemia of CKD.
Methods: Systematic review and meta-analysis of randomized controlled trials comparing IV iron preparation with oral iron preparation for the treatment of anemia in patients with CKD (stage III, IV and V). The Cochrane Library, MEDLINE, conference proceedings and references were searched until 2007. Primary outcomes: absolute hemoglobin (Hb) level or change in Hb level from baseline at two months or at end of study; all-cause mortality. Secondary outcomes: need for renal replacement therapy (RRT) in predialysis patient and adverse events. Weighted mean differences (WMD) for outcomes with continuous variables and relative risks (RR) for dichotomous outcomes with 95% confidence intervals (CI) were estimated and pooled.
Results: Our search yielded 11 trials which compared IV iron preparations (iron sucrose, iron gluconate or iron dextran) to oral iron. Compared to oral iron, there was a significant rise in Hb level in the IV iron treated hemodialysis patients (WMD 1.17; 95%CI 0.19–2.15, fig). Significant heterogeneity was observed due to different baseline Hb values and baseline iron status, different dosages of oral iron, and different dosages of erythropoiesis stimulating agents (ESA). For predialysis patients, there was a small but significant difference in the Hb level favoring the IV iron group (WMD 0.28; 95% CI 0.15–0.4, fig). For both groups effect estimates were not influenced by ESA administration. In predialysis patients, there was no significant difference in the risk for requiring RRT during the trial between the different groups (RR 0.63; 95%CI 0.25–1.65). Data on all-cause mortality were sparse (RR 0.54; 95%CI 0.09–3.13, 3 trials) and there was no difference in adverse events (RR 0.9; 95%CI 0.65–1.24) between the IV and oral treated patients. However, discontinuations of treatment were more common (RR 3.27; 95%CI 1.15–9.26) for the IV iron treated patients.
Conclusions: Our review demonstrates that dialysis patients treated with IV iron have better Hb response than patients treated with oral iron. For predialysis patients, this effect is very small. IV iron should be preferred in the treatment of anemia in dialysis patients. In predialysis patients the slight advantage in Hb response should be weighed against the inconvenience and cost of IV iron treatment.
