Has the pendulum swung too far? Discretionary single-unit red blood cell transfusion in trauma is associated with infection, thromboembolic events, and mortality.

Objectives: Studies in elective surgery report adverse outcomes with transfusion of a solitary unit of red blood cells (RBC). We quantified the effect of discretionary transfusion of one unit of blood in trauma patients with borderline transfusion indications. We hypothesized that transfusion of a discretionary unit of RBCs would increase complications.

Methods: Admitted adults from the 2017-2021 American College of Surgeons Trauma Quality Improvement Program database were included if they had an injury severity score between 10 and 25 and a Glasgow Coma Scale >8: moderately to severely injured patients. Associations between single-unit RBC transfusion in the first 4 h (with no subsequent transfusion) and three primary outcomes (mortality, infection, thromboembolic event) were assessed using inverse probability-weighting propensity matching with regression adjustment.

Results: A total of 649,841 patients were included in the study. Approximately 4.2% received one unit of RBC. Propensity matching (with fractional weighting) for transfusion resulted in 307,840.7 cases and 342,000.3 controls. Transfusion of a solitary unit of RBC was independently associated with each outcome: mortality (adjusted odds ratio [aOR] 2.11, 95% CI 1.66-2.69), infection (aOR 3.92, 95% CI 2.91-5.27), and thromboembolic event (aOR 2.02, 95% CI 1.55-2.64).

Conclusion: Transfusion of a single unit of RBC within the first 4 h of arrival in trauma patients with no subsequent transfusion during hospitalization was associated with an increased risk of mortality, infection, and a thromboembolic event. When weighing the decision to transfuse trauma patients with equivocal signs of hemorrhage, one needs to balance the potential harm against the likelihood that such transfusion is necessary.