The majority of our KPIs focused on measures to improve patient care around the time of decision to transfuse RBCs and transfusion safety (e.g. adherence to transfusion guidelines, measurement of Hb, sampling and labelling errors, inefficient use of RBCs) and on reducing the need for RBC transfusion (treating preoperative anaemia, use of tranexamic acid). This evidence concerns the gene GSTM1 and anemia.