In this retrospective case-matched study, the authors investigated the effect of red blood cell (RBC) transfusion on morbi/mortality in critically ill patients with moderate anemia (nadir hemoglobin: 7.0-9.5 g/dL). In 214 matched pairs, the authors observed higher rates of hospital mortality, ICU readmission, nosocomial infection and acute kidney injury in transfused patients. Similar results were obtained in subgroups of patients with severe anemia or patients with cardiovascular comorbidities.

While this study adds to other studies supporting a restrictive transfusion strategy in ICU patients, it has some bias related to the retrospective design and the types of patients included. In fact, the majority of patients were postsurgical patients (60%) with very low mortality and low severity scores. The reason for transfusion is not provided. Transfused patients were quickly (second day) transfused with the same hemoglobin value as day four of the non-transfused patients. In addition, the median hemoglobin was 9.4 g/dL for patients transfused in the cardiac group! Two RBC units per transfusion episode were administered. All of this can be suggestive of a pattern in transfusion practice rather than a pragmatic approach.

– Michael Piagnerelli