For assessment of changes in intraoperative red blood cell transfusion practices over time, the pooled incidence of transfusion correlates highly with total units transfused

Abstract

Study objective Multiple studies nationwide and at single hospitals have examined changes over time in the incidence of perioperative red blood cell (RBC) transfusion. However, the cost of RBC transfusions is related to the number of RBC units transfused, not to the incidence. We evaluate whether the readily available incidence of RBC transfusion can be used as a valid surrogate measure. Design Observational retrospective study. Setting One tertiary, academic hospital. Patients 394,789 cases of 1885 procedures over N = 42 quarters of the year. Interventions None. Measurement Incidence and number of RBC units transfused intraoperatively. Main results The number of RBC units transfused per case did not follow a Poisson distribution, confirming that the number of units and incidence of transfusion are not interchangeable for analyzing decisions by case. However, with all cases of each quarter combined, the Spearman correlation was 0.98 ± 0.01 between each quarter's incidence of RBC transfusion and mean RBC units transfused per case (P < 0.0001). Conclusions For assessment of changes in intraoperative RBC transfusion practices over years, it is sufficient to analyze the pooled incidence of transfusion, rather than to calculate the number of units transfused.