Recently, a joint working group of members of the International Haemovigilance Network, the International Society of Blood Transfusion and AABB concluded that it is too early to develop a consensus on TACO, its definition, its reporting criteria and its risk factors. This was due to the fact that currently, insufficient published research was available to guide practice or develop evidence-based guidelines. This paper on risk factors for TACO is a welcome addition to the literature.

Roubinian and co-workers identified 200 TACO cases among 20,845 transfused patients from four tertiary care hospitals from May 2015 to July 2016 in a case-control study (1 case:2 controls), and cases were matched by the number of transfusions. Despite no specific matching for gender, race, age and individual and mixed blood components, groups were similarly distributed. An automated screening algorithm was used to estimate TACO incidence.

The authors found an incidence of 1:100 transfused patients, which was lower than reported in previous literature. In addition, TACO occurred with fewer blood components than reported in earlier studies (mean of 2 compared to 3-6 units). A multivariable logistic regression model was used to evaluate risk factors for TACO. This analysis identified several risk factors (P < 0.05): cardiovascular (history of congestive heart failure or coronary artery disease, preexistent cardiomegaly on chest X-ray, elevated blood pressure at time of transfusion), renal (acute kidney injury, diuretic use prior to transfusion) and emergency surgery. Mortality in TACO cases was higher than in controls (21% versus 11%; P < 0.02), after controlling for potential confounding variables. This should be interpreted with caution, since there is no evidence for causality and due to the observational nature of this study bias and residual confounding may occur. Interestingly, TACO occurred more often after plasma transfusions and more often in females (significant interaction). With the finding of several potential clinical risk factors, the benefit of single-unit transfusions, diuretic dosing and timing, and alternatives for plasma transfusions should be further explored in the prevention of TACO. – Cynthia So-Osman