Blood transfusions have been found to increase the risk of postoperative complications in surgical patients. The aim of this study was to investigate the effect of blood transfusions on postoperative morbidity and mortality in patients undergoing lower extremity bypass procedures using the National Surgical Quality Improvement Program database. The National Surgical Quality Improvement Program database was queried for years 2014 to 2016 for lower extremity bypass and angioplasty procedures using Current Procedural Terminology codes 37220 through 37235. Cohorts were based on having received a transfusion or not. Cohorts were case matched according to age, sex, race, smoking, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, congestive heart failure, chronic kidney disease, and ventilator dependence. To assess association between perioperative blood transfusions and postoperative morbidity and mortality, a binary logistic regression test in a stepwise fashion and a two-step cluster were performed. A total of 3492 patients were included in the final analysis after case matching, with 1164 receiving transfusion. Among patients who underwent lower extremity revascularization, those who received intraoperative or postoperative blood transfusion showed a higher risk of pneumonia (relative risk [RR], 3.7; P < .001), unplanned reintubation (RR, 4.3; P < .001), prolonged intubation >48 hours (RR, 4.7; P < .001), sepsis (RR, 2.8; P < .001), septic shock (RR, 5.3; P < .001), superficial surgical site infection (RR, 4.1; P < .001), deep surgical site infection (RR, 4; P = .003), organ/space surgical site infection (RR, 5.3; P = .006), acute kidney injury (RR, 7.3; P < .001), deep venous thrombosis or thrombophlebitis (RR, 2.25; P = .015), postoperative myocardial infarction (RR, 4.6; P < .001), cerebrovascular accident or stroke (RR, 2.3; P < .03), and 30-day postoperative mortality (RR, 3.6; P < .001). Of interest, the complications experienced by transfusion were predictable based on preoperative condition. Cluster quality was rated good at 0.8 based on silhouette measure of cohesion and separation. The Table describes the relationship between the patient’s preoperative profile and the odds of specific transfusion reactions. Blood transfusions increase risk of postoperative morbidity and mortality among patients who undergo lower extremity bypass procedures. Complications follow a predictable pattern based on the patient’s characteristics, which may aid in care.TableIndependent predictors of postoperative complications among blood transfusion group patientsPostoperative complication (predictor)Odds ratio95% CIP valuePneumonia COPD2.21.2-3.9.007 Congestive heart failure2.41.2-5.018Reintubation Sex (male)1.81.04-3.1.035 COPD2.41.3-4.5.004AKI Sex (male)2.71.06-6.8.036 Diabetes mellitus2.91.1-7.5.021 COPD4.51.8-10.9.001Sepsis Diabetes mellitus2.21.1-4.3.018AKI, Acute kidney injury; CI, confidence interval; COPD, chronic obstructive pulmonary disease. Open table in a new tab