EFFECT OF ANEMIA AND CARDIOVASCULAR-DISEASE ON SURGICAL MORTALITY ANDMORBIDITY

Background Guidelines have been offered on haemoglobin thresholds for blood transfusion in surgical patients. However, good evidence is lack ing on the haemoglobin concentrations at which the risk of death or se rious morbidity begins to rise and at which transfusion is indicated. Methods A retrospective cohort study was performed in 1958 patients, 1 8 years and older, who underwent surgery and declined blood tranfusion for religious reasons. The primary outcome was 30-day mortality and t he secondary outcome was 30-day mortality or in-hospital 30-day morbid ity. Cardiovascular disease was defined as a history of angina, myocar dial infarction, congestive heart failure, or peripheral vascular dise ase. Findings The 30-day mortality was 3.2% (95% CI 2.4-4.0). The mort ality was 1.3% (0.8-2.0) in patients with preoperative haemoglobin 12 g/dL or greater and 33.3% (18.6-51.0) in patients with preoperative ha emoglobin less than 6 g/dL. The increase in risk of death associated w ith low preoperative haemoglobin was more pronounced in patients with cardiovascular disease than in patients without (interaction p<0.03). The effect of blood loss on mortality was larger in patients with low preoperative haemoglobin than in those with a higher preoperative haem oglobin (interaction p<0.001). The results were similar in analyses of postoperative haemoglobin and 30-day mortality or in-hospital morbidi ty. Interpretation A low preoperative haemoglobin or a substantial ope rative blood loss increases the risk of death or serious morbidity mor e in patients with cardiovascular disease than in those without. Decis ions about transfusion should take account of cardiovascular status an d operative blood loss as well as the haemoglobin concentration.