Association between intraoperative blood transfusion and postoperative delirium in elderly patients undergoing total hip arthroplasty with combined spinal-epidural anesthesia: an IPTW-adjusted retrospective cohort study

Perioperative blood transfusion has been considered a potential risk factor for postoperative delirium (POD) in elderly patients. However, the association remains controversial, and prior studies have lacked a quantitative evaluation of the dose–response relationship. This single-center retrospective cohort study included 610 patients aged 65 years or older who underwent their first total hip arthroplasty between January 2020 and April 2025. Patients were stratified into three groups according to intraoperative red blood cell transfusion volume: no transfusion, low-volume transfusion (< 4 units), and high-volume transfusion (≥ 4 units). Propensity score–based inverse probability of treatment weighting (IPTW) was utilized to control for baseline confounding and to evaluate the association between intraoperative transfusion and POD. IPTW-adjusted multivariable regression analysis revealed that overall transfusion was not associated with POD, but a significant dose–response was found when transfusion volume was stratified. The incidence of POD was significantly higher in the high-volume transfusion group compared with the no transfusion group (15.4% vs. 4.3%; adjusted odds ratio [OR] = 5.09, 95% confidence interval [CI]: 1.24–20.81; P = 0.024). Age ​was identified as​ a significant effect modifier (interaction P = 0.049), with patients aged 75 years or older exhibiting a heightened transfusion-related risk of POD. In this retrospective study of older patients undergoing THA with CSEA, intraoperative high-volume transfusion was associated with an increased risk of POD compared with no transfusion.