Development of a Predictive Algorithm for a Hemoglobin Value of Less Than 10 g/dl Postoperatively in Scheduled Hip or Knee Arthroplasty

Hip (THR) or knee (KT) prosthetic surgery is a bleeding surgery with an average blood spoliation of about 1 liter and an average decrease of about 3 g/dl in hemoglobinemia (Hb). Consequently, anemia is observed postoperatively in almost all patients (between 85% and 99% depending on the preoperative Hb value). In all cases, anemia-related events delay the patient's recovery, favor the occurrence of complications and prolong the length of stay. The immediate treatment of acute postoperative anemia is based on transfusion of red blood cells (RBCs). However, this presents several risks for the patient. The first is immediate and associated with the procedure: risk of error with ABO/Rhesus incompatibility, sepsis, pulmonary edema, etc. The second is a medium-term risk, with an increased risk of infection after prosthetic hip or knee surgery. In the long term, immediate postoperative blood transfusion is associated with higher mortality. In order to reduce the likelihood of a patient receiving RGCs, strategies have been developed within a "Patient Blood Management" (PBM), which could be translated as "Personalized Blood Transfusion Management". This strategy is based on 3 pillars: preoperatively, to ensure a patient's hemoglobin level of at least 13 g/dl; during the procedure, to limit blood loss; and postoperatively, to limit the indications for blood transfusion and the number of RGCs to the strict necessary. As the main determinant to trigger the prescription of a blood transfusion is the Hb value, the objective is that the lowest value of hemoglobinemia (Hb\_nadir) postoperatively is as close as possible to 10 g/dl. The objective of this study is to describe, by means of the data available in the computerized patient record of patients undergoing scheduled THR or PTG operations at the Paris Saint Joseph Hospital, a prediction equation for Hb\_nadir \< 10 g/dl and, thus, to prescribe iron and ESAs only in patients who require them.