Association of antepartum anemia and red blood cell mass with racial and ethnic disparities in transfusion rates after cesarean delivery: A retrospective cohort study

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BACKGROUND: Antepartum anemia among patients undergoing cesarean deliveries has increased over the past decades in the United States. We hypothesized that red blood cell (RBC) mass, reflecting both prepartum anemia and body mass index (BMI), predicts transfusion risk after cesarean delivery beyond racial/ethnic categories. STUDY DESIGN AND METHODS: A retrospective analysis of cesarean deliveries from 2019 to 2021 was performed using the National Surgical Quality Improvement Program database. The outcome of interest was perioperative transfusion within 72 h of surgery. Multivariable logistic regression models evaluated the potential added predictive value of race and RBC mass, alongside other known predictors of transfusion. RESULTS: Among 43,869 cesarean deliveries, the perioperative RBC transfusion rate was 3.3%. Anemia and high BMI were the most prominent in Blacks and Native Americans. These two racial groups had a significantly larger RBC mass difference between non-transfused and transfused individuals (ΔRBC mass, 360-400 mL). Cesarean deliveries for placental complications had six-fold higher transfusion odds than those with only a history of cesarean delivery. While race remained a significant predictor, a 400 mL increase in RBC mass was associated with a 35% decrease in transfusion odds. DISCUSSION: Antepartum anemia prevalence and BMI varied significantly by race/ethnicity, influencing peripartum RBC mass and transfusion rates. Despite the association of races or placental factors, our predictive model demonstrated a significant reduction of transfusion odds with increased antepartum RBC mass. As a parameter that accounts for varied hemoglobin levels and BMI, estimated RBC mass may be a useful metric for assessing transfusion risk in diverse populations.