No Link Between Red Blood Cell Transfusion, VTE After Major Surgery

HONOLULU—Perioperative allogeneic red blood cell (RBC) transfusion is not associated with increased risk for postoperative venous thromboembolism (VTE) following major surgery, a study presented at the 2025 annual meeting of the International Anesthesia Research Society has concluded.

“There is evidence that a significant association exists between allogeneic RBC transfusion and an increased risk for postoperative VTE,” said Xiaohan A. Xu, MD, an instructor of anesthesia at Beth Israel Deaconess Medical Center, in Boston. “And even though the simultaneous administration of procoagulant agents such as fresh frozen plasma may confound this association, most studies didn’t take plasma transfusions into consideration. So, we don’t know whether the plasma is causing problem or the RBCs.”

As such, the aim of the study was to investigate the association between RBC transfusion and postoperative VTE among patients undergoing major surgeries. The retrospective cohort study included 83,478 patients, all of whom underwent major surgery at a university-affiliated hospital in Beijing, China, between 2018 and 2022. The exposure of interest was allogeneic RBC transfusion products; the primary end point was postoperative VTE.

Of the original cohort, 8,372 patients (10%) received perioperative RBC transfusion, and postoperative VTE was found to occur in 905 patients (1.1%). After adjusting for a number of potential confounders, multivariable logistic regression models found no significant association between RBC transfusion and VTE, yielding an odds ratio (OR) of 1.0 (95% CI, 0.78-1.33; P=0.893). Similar results were found with propensity score overlap weighting analysis.

Although subgroup analyses indicated a significant interaction between RBC transfusion and surgery type on the risk for VTE (P<0.001), RBC transfusion was not associated with postoperative VTE within any individual surgery type. Similarly, the association between RBC transfusion and VTE was not significantly interacted with fresh frozen plasma transfusion (P=0.612), a finding that remained nonsignificant in subgroups of patients who did or did not receive fresh frozen plasma transfusion.

The investigators also performed a dose–response analysis, which revealed a significant trend of increasing postoperative VTE risk with greater amounts of transfused RBCs (P=0.044). Specifically, patients receiving greater than 6 units of RBCs had a significantly higher risk for postoperative VTE than did their counterparts who were not transfused (OR, 1.51; 95% CI, 1.00-2.29). Lower amounts of RBC transfusion were not significantly associated with VTE risk.