Garfinkle et al. [53] also published a systematic review on 11 observational studies that enrolled 290,847 patients with acute coronary syndrome: the unadjusted OR of mortality in transfused patients ranged from 1.9 to 11.2; a meta-analysis was not performed because there was too much heterogeneity, but the data suggested a protective effect of RBC transfusion if nadir Hb drops below 80 g/L and neutral or harmful effects above 110 g/L. Here, GSTM1 is linked to acute coronary syndrome.