Effects of red blood cell transfusions given to non-septic critically ill patients: a propensity score matched study

Introduction
Previous studies have demonstrated that low-grade red blood cell transfusions (RBC) given to septic patients are harmful. The objectives of the present study were to compare mortality and morbidity in non-septic critically ill patients who were given low-grade RBC transfusions at haemoglobin level > 70 γ L–1 with patients without RBC-transfusions any of the first 5 days in intensive care.

Material and methods
Adult patients admitted to a general intensive care unit between 2007 and 2018 at a university hospital were eligible for inclusion. Patients who received > 2 units RBC transfusion per day during the first 5 days after admission, with pre-transfusion haemoglobin level < 70 γ L–1 or with severe sepsis or septic shock, were excluded.

Results
In total, 9491 admissions were recorded during the study period. Propensity score matching resulted in 2 well matched groups with 674 unique patients in each. Median pre-transfusion haemoglobin was 98 γ L–1 (interquartile range 91–107 γ L–1). Mortality was higher in the RBC group with an absolute risk increase for death at 180 days of 5.9% (95% CI: 3.6–8.3; P < 0.001). Low-grade RBC-transfusion was also associated with renal, circulatory, and respiratory failure as well as a higher SOFA-max score. Sensitivity analyses suggested that disease trajectories during the exposure time did not significantly differ between the groups.

Conclusions
Low-grade RBC-transfusions given to non-septic critically ill patients without significant anaemia were associated with increased mortality, increased kidney, circulatory, and respiratory failure, as well as higher SOFA-max score.