Figure 2
Meta-analysis of the role of pre-operative iron on anaemia outcomes in patients undergoing abdominal surgery. Forest plot comparing pre-operative iron versus no pre-operative iron or placebo before abdominal surgery. Each horizontal bar summarizes a study. The bars represent 95% confidence intervals. The grey squares inform on each of the studies’ weight in the meta-analysis. The diamond in the lower part of the graph depicts the pooled estimate along with 95% confidence intervals. Pooled relative risk (RR), risk difference (RD) and mean difference (MD) were obtained using models with random effects. Heterogeneity was assessed using the Q-test and quantified using the I2 value. Risk of bias was assessed by using the Cochrane Collaboration’s tool for assessing risk of bias. (A) MD in haemoglobin concentration at admission, (B) RD for peri-operative allogeneic blood transfusion, (C) RR for peri-operative allogeneic blood transfusion. Data for the RCT by Richards et al. were extracted from Table 2 of their article including large blood transfusions for the number of patients who received blood transfusion, and reconstituted from the text (which reported a MD of 4.7 g/l and from Figure 2 for the mean haemoglobin concentration).
