WHAT IS KNOWN AND OBJECTIVE To evaluate the efficacy and safety of intravenous iron supplementation in patients with renal anaemia. METHODS We searched the PubMed, Embase, Cochrane Library, and Web of Science from their inception until 17 September 2021, for randomized controlled trials (RCTs) to evaluate the efficacy and safety of intravenous iron at different frequencies. The observed efficacy indicators
included transfer saturation (TSAT), serum ferritin (SF) and haemoglobin (HGB). Outcomes of interest included allergies, infections, all-cause mortality and cardiovascular events. RESULTS AND DISCUSSION Of the 751 eligible studies, 7 RCTs met the inclusion criteria. The RCTs showed that there were no significant differences between the low-frequency high-dose group (1-2 doses, >200 mg/dose) and the high-frequency low-dose group (4-5 doses, ≤200 mg/dose) in the increase in TSAT (WMD = 1.90; 95% CI = -2.04 to 5.84; I(2) = 0%), SF (WMD = 15.70; 95% CI = -32.20 to 70.61; I(2) = 0%) and HGB (WMD = -0.00; 95% CI = -0.43 to 0.42; I(2) = 0%). There was also no significant difference in the occurrence of outcome events, including allergies (RR = 1.84; 95% CI = 0.95 to 3.57; I(2) = 45%), infections (RR = 0.61; 95% CI = 0.20-1.86; I(2) = 0%), cardiovascular events (RR = 0.88; 95% CI = 0.67-1.15; I(2) = 48%) and all-cause mortality (RR = 0.74; 95% CI = 0.40-1.35; I(2) = 0%). WHAT IS NEW AND CONCLUSION Frequencies of intravenous iron supplementation with similar doses share similar safety and efficacy in patients with renal anaemia. However, a single dose or two doses of intravenous iron are more cost-effective and patient friendly. These findings may provide evidence for the clinical application of intravenous iron supplementation for patients with renal anaemia.