Risk Factors for Post-Operative Blood Transfusion Following Total Knee Arthroplasty

As the population ages, rate of total knee arthroplasty increases and thus, it is important to maximize efficiency and minimize risk. Identifying patients who are at higher risk for transfusion can help streamline care provided and minimize superfluous, costly hemoglobin monitoring in low risk patients.

Adult patients who underwent total knee arthroplasty (TKA) in 2015 were identified in the National Surgical Quality Improvement Project (NSQIP) database. Patients were divided into two cohorts: those who required transfusion post operatively and those who did not. Patient demographics and comorbidities were compared using univariate analysis; and multivariate analysis was used to determine risk factors for short-term complications.

Of 48,055 TKA patients, 3.0% required transfusion. The patients who required transfusion were older, had higher BMI, higher rates of comorbidities and were more frequently ASA class 3-4 (p<0.005). Univariate analysis revealed that patients who required transfusion had higher rates of any complication (9.19% v. 4.23%, p<0.001). Multivariate regression analysis identified the following as risk factors for transfusion requirement: Black race (adjusted odds ratio [OR] 1.2, 95% confidence interval [CI] 1.01-1.4), COPD (OR 1.6, 95% CI 1.3-2.0), corticosteroids (OR 1.4, 95% CI 1.1-1.8), bleeding disorder (OR 1.4, CI 1.1-1.9), ASA class 4 (OR 2.3, CI 1.5-4.8), operative time >2 hours (OR 1.3, 95% CI 1.2-1.5) and lack of functional independence (OR 1.6, 95% CI 1.1-2.3).

In a cohort of patients undergoing primary TKA in 2015, history of COPD, black race, operative time, steroid use, bleeding disorder, lack of functional independence and ASA class 3-4 were independent predictors of need for blood transfusion. Additionally, we found that patients who received transfusion demonstrated a significantly higher rate of the following: any complication, pneumonia, urinary tract infection, septic shock, deep vein thrombosis, renal insufficiency, cardiac arrest, myocardial infarction, unplanned readmission, reoperation and mortality. Presence of these risk factors in TKA patients could represent an indication for hemoglobin monitoring post-operatively.Level of Evidence: IV.