The prevalence and association with transfusion, intensive care unit stay and mortality of pre-operative anaemia in a cohort of cardiac surgery patients

Anaemia is increasingly prevalent in the United Kingdom. Despite recommendations to the contrary, many patients undergo cardiac surgery with undiagnosed and untreated anaemia. According to the World Health Organization definition, 1463/2688 (54.4%) patients undergoing cardiac surgery between 2008 and 2009 in our institution were anaemic. Compared with non-anaemic patients, anaemia was significantly associated with transfusion (791 (54.1%) vs 275 (22.4%), p < 0.001, OR (95% CI) 3.4 (2.8-4.1)), death (45 (3.1%) vs 13 (1.1%), p = 0.0005, OR 2.4 (1.2-4.5)), and prolonged ICU stay (287 (19.6%) vs 168 (13.7%) p < 0.001, OR 1.3 (1.0-1.6)). The prevalence of anaemia in this cohort is much greater than that previously reported. The cause of this excess is not clear. Pre-operative anaemia is a strong predictor of increased transfusion requirement, risk of ICU stay and death during cardiac surgery. The effect of increasing haemoglobin concentration therapeutically is not yet clear.