Eight RCTs were included in the meta-analyses (1,606 participants): seven phase III trials and one phase II trial. Twenty-two arms were available for comparison.
Haematopoietic response: The risk of obtaining a haematopoietic response was significantly increased with parenteral iron compared with no iron (RR 1.29, 95% CI 1.13 to 1.48; Ι²=63%; seven RCTs). No between-group difference was found for oral iron versus no iron (three RCTs) or for parenteral iron versus oral iron (four RCTs).
When the type of ESA was considered, a greater increase in haematopoietic response was found for epoetin (RR 1.85, 95% CI 1.43 to 2.39; Ι²=32%) than darbepoetin (RR 1.18, 95% CI 1.10 to 1.27; Ι²=6%) with parenteral iron. No significant differences were found with oral iron.
Transfusion rates: The risk of transfusion was significantly reduced with parenteral iron compared with no iron (RR 0.77, 95% CI 0.62 to 0.97, Ι²=0%; seven RCTs).
When type of ESA was considered, a significant reduction was found when parenteral iron was associated with darbepoetin but not with epoetins.
No statistically significant difference of risk of transfusion was found between oral iron and no iron (three RCTs) or between parental iron and oral iron (three RCTs).