Predicting need for allogeneic transfusion after total knee arthroplasty.

Total knee arthroplasty (TKA) can lead to substantial blood loss. To avoid the high costs of autologous blood predonation programs and efficiently allocate limited blood resources, we sought to identify preoperative and intraoperative factors associated with allogeneic blood transfusion (AllTx) after primary TKA and, subsequently, develop a model to predict patients who will require AllTx. We analyzed 31 independent variables in 644 primary unilateral TKAs without autologous blood predonation for requirement of AllTx. Seventy-one procedures (11.0%) required AllTx. Age, comorbid anemia, preoperative hemoglobin concentration, and surgical time were significant predictors for requiring AllTx. When applied to an independent cohort, our model for predicting the need for AllTx after TKA was 90% sensitive and 52.5% specific.