Restrictive Versus Liberal Transfusion Strategies for Cardiac Surgery

Abstract

Background: Anaemia is an important complication affecting cardiac surgery patients. Following cardiac surgery, transfusion of red blood cells is often required for haemodynamic support. Traditionally, haemoglobin cutoffs of 9–10 g/dL were used for to trigger transfusion. New randomised trial evidence has recently bolstered support for restrictive protocols with haemoglobin cutoffs of 7–8 g/dL. Methods: A best evidence topic was written addressing the question “does post-operative mortality among adult patients undergoing cardiac surgery differ with restrictive versus liberal transfusion strategies?” Altogether, ten randomised trials representing 11,826 patients were identified searching Medline, Embase, and Pubmed databases from 1980 to February 2019 which represented the best evidence to answer the question. Results: Some older trials have suggested a trend toward long-term mortality benefit with liberal transfusion protocols: Hazard Ratio (HR) 0.7 [95% confidence interval (CI) 0.49–1.02, p = 0.06] from a meta-analysis summarising six trials. However, more recent, larger, high-quality contemporary trials have demonstrated noninferiority with regard to mortality for a restrictive strategy, with the largest of which producing an odds ratio of 0.85 (95% CI 0.62–1.16) for 28-day mortality and 1.02 (95% CI 0.87–1.18, p = 0.006) for 6-month mortality. Conclusions: Among cardiac surgery patients, restrictive and liberal transfusion strategies do not differ with respect to mortality. Adverse outcomes such as stroke, nonfatal myocardial infarction, and renal failure did not differ between the two groups. Restrictive strategies result in fewer transfusions and less health care expenditure.