Efficacy of oral vs. intravenous iron for the treatment of iron deficiency anemia in different conditions: A systematic review and meta‑analysis

The present systematic review and meta-analysis evaluated the efficacy and safety of oral vs. intravenous (IV) iron therapy in managing iron deficiency anemia (IDA) across various clinical conditions. A comprehensive search was conducted in PubMed/MEDLINE, EMBASE, Cochrane CENTRAL, Web of Science, Scopus, and ClinicalTrials.gov, yielding 31 eligible studies. IV iron demonstrated statistically significant superiority over oral iron in increasing hemoglobin levels among patients with chronic kidney disease (CKD), inflammatory bowel disease (IBD), cancer-related anemia and general IDA. Specifically, pooled standardized mean differences (SMD) indicated significant improvements with IV iron for cancer-related anemia (SMD: -0.662, P=0.011), CKD (SMD: -0.492, P=0.035), IBD (SMD: -0.560, P<0.001) and IDA (SMD: -0.397, P<0.001). However, no significant differences were observed for postoperative anemia or restless legs syndrome. IV iron consistently provided faster hemoglobin correction and fewer gastrointestinal side effects compared with oral iron; however, higher costs and logistical requirements may limit its widespread use. Meta-regression analysis revealed that neither treatment duration nor dosage significantly influenced treatment outcomes, highlighting the role of patient-specific factors in determining the efficacy of iron therapy. Despite substantial heterogeneity, sensitivity and publication bias analyses confirmed the robustness of the findings. Overall, IV iron therapy is the preferred choice in conditions with impaired iron absorption or urgent clinical needs, whereas oral iron remains suitable for mild to moderate cases.