International variation in the use of blood transfusion in patients with non-ST-segment elevation acute coronary syndromes.

The purpose of this study was to determine international patterns of blood transfusion in patients with acute coronary syndrome (ACS). Previous studies showed geographic heterogeneity in some aspects of ACS care. Data for variability in the use of blood transfusion in ACS management are limited. Pooled data from 3 international randomized trials of patients with non-ST-segment elevation ACS (n = 23,906) were analyzed to determine the association between non-United States (US) location and blood transfusion after stratifying by the use of invasive procedures. The analysis adjusted for differences in patient characteristics and was repeated using a 2-stage mixed-model approach and in patients who underwent in-hospital coronary artery bypass grafting. Compared with US patients, both unadjusted and adjusted hazards for blood transfusion were significantly lower in non-US patients who did not undergo invasive procedures (unadjusted hazard ratio [HR] 0.23, 95% confidence interval [CI] 0.17 to 0.33; adjusted HR 0.20, 95% CI 0.14 to 0.28). This was also true in non-US patients who underwent invasive procedures (unadjusted HR 0.34, 95% CI 0.27 to 0.44; adjusted HR 0.31, 95% CI 0.23 to 0.42). Results were similar in both validation analyses. In conclusion, there was substantial international variation in blood transfusion use in patients with ACS. These results, along with the controversy regarding the appropriate use of transfusion in patients with coronary heart disease, emphasize the need for understanding the role of blood transfusion in the management of patients with ACS and factors that influence transfusion decisions.