Evaluating the Effect of Decreasing Preoperative Hemoglobin on Blood Transfusions, Major Complications, and Periprosthetic Joint Infection After Primary Total Knee Arthroplasty.

INTRODUCTION: Preoperative anemia is associated with increased postoperative transfusion and complication rates after total knee arthroplasty (TKA). We aimed to create TKA-specific data-driven preoperative hemoglobin strata that quantify the likelihood of 90-day postoperative blood transfusion and evaluate whether these strata are associated with increased risk of 90-day major complications and 2-year prosthetic joint infection (PJI).

METHODS: Primary TKA patients from 2013 to 2022 were identified using a national database. Stratum-specific likelihood ratio (SSLR) analysis defined hemoglobin strata associated with the risk of 90-day blood transfusion. Each stratum was propensity score matched to the highest identified hemoglobin strata. Unmatched incidence rates and matched risk of 90-day major complications and 2-year PJI between strata were compared.

RESULTS: SSLR identified four 90-day blood transfusion hemoglobin strata for men (strata [g/dL], likelihood ratio [<11.4, 8.06; 11.5 to 11.9, 4.34; 12.0 to 12.9, 1.70; 13.0 to 17.0, 0.54]) and women (<10.4, 8.22; 10.5 to 11.4, 2.84; 11.5 to 12.4, 1.38; 12.5 to 17.0, 0.50). Increased 2-year PJI risk was associated with three male strata (<11.4, 11.5 to 11.9, 12.0 to 12.9; all P < 0.001) and three female strata (<10.4, 10.5 to 11.4, 11.5 to 12.4; all P < 0.001). Increased 90-day major complication risk was associated with three male strata (<11.4, 11.5 to 11.9, 12.0 to 12.9; all P < 0.001) and three female strata (<10.4, 10.5 to 11.4, 11.5 to 12.4; all P < 0.001).

CONCLUSIONS: Using SSLR analysis, we identified unique TKA-specific data-driven hemoglobin strata for both men and women that quantify the likelihood of 90-day blood transfusions and predict the risk of both 90-day major complications and 2-year PJI. These strata are a first in the TKA literature and can assist surgeons in stratifying patients' transfusion and complication risk based on their preoperative hemoglobin value. While optimizing patients in the preoperative setting, we recommend using these TKA-specific hemoglobin thresholds to help guide decision making on the need for presurgery anemia optimization and to help reduce the need for blood transfusion.