Fig. 4From: Iron supplementation to treat anaemia in adult critical care patients: a systematic review and meta-analysisSubgroup analysis: effect of iron supplementation by either intravenous or oral administration on allogeneic red blood cell transfusion requirement a oral iron versus no iron, b intravenous iron versus no iron. RBC red blood cell, CI confidence interval, M-H Mantel-Haenszel testBack to article page