Preoperative haemoglobin concentration and mortality rate after coronary artery bypass surgery.

We did an observational study in 2059 patients undergoing coronary artery bypass surgery to assess the effect of haemoglobin concentration on in-hospital mortality. We noted that individuals with a preoperative haemoglobin concentration of 100 g/L or less had a five-fold higher in-hospital mortality rate after surgery than those with a higher haemoglobin concentration, despite having had blood transfusions or the pump primed with blood preoperatively as a routine precaution. Our findings suggest that a low haemoglobin concentration is a marker of disease severity or comorbidity that has a major effect on survival rate.