How have red blood transfusion practices changed in critically ill patients? A comparison of the ICON and ABC studies conducted 13 years apart

Background: Optimal transfusion practice remains a matter of ongoing debate despite several large clinical studies.

Study design and methods: Databases from two observational studies-the Anemia and Blood Transfusion in Critically ill patients (ABC) conducted in 1999 and The Intensive Care Over Nations (ICON) audit conducted in 2012-were compared to evaluate changes in transfusion practice and outcomes over a 13-year period.

Results: A total of 3534 patients from the ABC study and 4125 from the ICON study were included in this analysis. ICON patients were more severely ill, with higher APACHE II and sequential organ failure assessment (SOFA) scores on admission than ABC patients; however, ICU mortality rates were similar (13.5% vs 13.8%, P = .745). The ICU transfusion rate was significantly lower in the ICON study (24% vs 37%, P < .001). APACHE II and SOFA scores were significantly higher in transfused patients in the ICON study than those in the ABC study (APACHE II: 22.0 ± 8.1 vs 16.5 ± 7.9, P < .001; SOFA: 8.4 ± 4.0 vs 6.6 ± 3.7, P < .001), but mortality rates were similar. Twenty-eight day mortality rates for patients who received more than 4 RBC units were lower in the ICON study (33.6% vs 44.8%, P = .006).

Conclusion: The transfusion rate in ICU patients decreased during the 13-year period, despite patients being more severely ill in the more recent study; ICU mortality rates remained relatively stable. In patients who received more than 4 units of blood, the mortality rate was significantly lower in the more recent database.