Determinants of transfusion decisions in the ICU: haemoglobin concentration, what else? - a retrospective cohort study

Background and Objectives The aim of this study was to assess potentially relevant clinical characteristics which influence the decision to transfuse red cells in critically ill patients with low haemoglobin concentrations (6.0-10.0 g/dl). Materials and Methods This was a retrospective observational cohort study of patients admitted between November 2004 and May 2016 at the intensive care unit (ICU) of the Leiden University Medical Center, Netherlands. Haemoglobin measurements, clinical variables and the subsequent transfusion decision were extracted from the electronic health records. Clinical variables were grouped by organ system. We first examined the association of each of the clinical variables with the decision to transfuse during the following 6 h after a haemoglobin measurement using generalized estimating equations. We then compared the predictive abilities of single variables within an organ system and the predictive ability of an organ system's combined variables using the change in Akaike information criterion (AIC). Results A total of 83 394 haemoglobin measurements of 10 947 ICU admissions were included. Haemoglobin concentration was the most predictive for red cell transfusion. After the haemoglobin concentration, the combined variables for General Health, followed by the organ systems Cardiovascular and Pulmonary, were most predictive for red cell transfusion. Within these organ systems, the APACHE II score, referring department, APACHE admission diagnosis subgroup, troponin concentration, lactate concentration, respiratory rate, PaO2/FiO(2) and ventilation mode had the highest predictive ability. Conclusion Haemoglobin concentration is the dominant predictor for red cell transfusion. Other clinical characteristics are also predictive, though to a lesser extent.