Wide Variation in Transfusion Practices Seen Locally and Globally

A median of 84% of intensive care units (ICUs) administered red blood cell (RBC) transfusions to critically ill patients with hemoglobin (Hb) levels greater than 7 g/dL in a prospective international study published in JAMA.  

In addition, the average Hb level throughout ICU stay was 8.7 g/dL for patients who received at least one unit of RBCs (compared with 11.4 g/dL for those not transfused). The lowest Hb level during ICU stay was 7.6 g/dL (compared with 10.8 g/dL for those not transfused). 

The newest AABB International Red Blood Cell Transfusion Guidelines, published in the same issue of JAMA, recommend a transfusion threshold of 7 g/dL for most patients — including those in the ICU. Despite guidance from AABB and similar international organizations, the authors noted considerable uncertainty about best strategies for transfusion management (restrictive versus liberal) among different patient populations and about the clinical reasons and physiologic triggers used to make decisions about whether to transfuse. 

This study was conducted to understand RBC transfusion practices by center, country and continent. The primary outcome was the occurrence rate of RBC transfusion during ICU stay. Transfusion was defined as receiving one or more RBC units. The study included 3,643 ICU patients at 243 centers in 30 countries in six continents. Of these, 150 patients were in Africa, 182 in Asia, 2,167 in Europe, 50 in South America, 167 in North America and 927 in Oceania. Nineteen of the included countries were classified as high-income, five as upper middle-income and six as lower-middle income. 

The researchers found wide variation in the proportion of patients who received transfusion in the ICU. Overall, a quarter of patients received a transfusion. By center, rates varied from 0% to 100% of patients. By country, the proportion ranged from 0% to 80%; by continent, the proportion ranged from 19% to 45%. Median pretransfusion Hb levels ranged from5.3g/dL to 9.1 g/dL across countries; across continents, levels ranged from 7.2 g/dL to 8.7 g/dL. 

The researchers also examined clinical reasons and physiological triggers given for transfusion. The main stated clinical reasons for transfusion across all patients were low Hb level in (81.8%), active bleeding (27.7%), and hemodynamic instability (23.5%). In terms of the main stated physiological triggers, hypotension was most common (42.2%), followed by tachycardia (27.4%), and increased lactate level (17.8%). Notably, no physiologic trigger was given for the decision to transfuse in 39.5% of 1,727 transfusion events. Low Hb value, active bleeding, and hemodynamic instability were the most common clinical reasons for transfusions in all regions except Africa, where 33% of RBC transfusions were given to improve the patient’s general state. 

In a related editorial, Matthew D. Neal, MD, of the University of Pittsburgh; and Beverley J. Hunt, MD, of Guy’s and St. Thomas’ NHS Foundation Trust in London, observed that variation in transfusion practice was documented in the 1993 Safe and Good Use of Blood in Surgery (SANGUIS). In that study, transfusion rate was found to be influenced more by the individual clinician than on the type of procedure, patient population or hospital. This variation still exists today, as evidenced by this 2023 study. “Why does such variation persist?” they asked. “The reasons for the large variability of transfusion practice remain elusive, and clinicians’ attitudes appear slow to change. Patient blood management guidelines exist but are not well implemented. Barriers include access to knowledge, beliefs about the intervention and tension for change.”