The Influence of Preoperative Anemia on Clinical Outcomes After Infrainguinal Bypass Surgery

Background: Anemia is associated with greater mortality and complications in cardiovascular surgery. Within chronic limb-threatening ischemia, the effect of anemia is becoming apparent. This study aimed to further understand the influence of anemia in patients undergoing surgical revascularization for lower limb ischemia. Methods: A retrospective review of all patients undergoing infrainguinal surgical revascularization between 2016 and 2018 at a tertiary center was performed. Anemia was defined as an hemoglobin (Hb) level of less than 120 g/L. The primary outcome was overall survival by the Kaplan-Meier analysis. Secondary outcomes included length of hospital stay, blood transfusion requirements, wound infection, myocardial infarction, and limb-loss and all-cause mortality. The Cox proportional-hazard analysis and receiver operating characteristics (ROC) were performed. Results: A total of 124 patients were followed-up for a mean of 23(8) months. Forty-five patients were anemic. There were comparable baseline demographics, comorbidity, and severity of symptoms. Overall survival was significantly worse (logrank P < 0.01) in the anemic group as was the duration of stay, 27 (23) days vs. 14 (16) days (P = 0.001). Patients with anemia received more blood transfusions, 19 (42%) compared with 13 (16.5%) (P = 0.001), and had more cardiac complications (11.1% vs. 3.8%) (P = 0.02). Surgical site infection rates were also higher (20% vs. 6.3%; P = 0.036). There was no difference in graft patency or subsequent ipsilateral major lower extremity amputation. Thirty-day mortality was comparable between the anemic versus the nonanaemic groups, 3 (6.7%) vs. 1 (1.3%) (P = 0.132). At 1 year, there was a higher mortality rate in the anemic group of 8 (18%) vs. 4 (5%) in the nonanaemic group (P = 0.037), which persisted to the long term. Anemia was independently associated with mortality; hazard ratio 4.0 (1.14-12.1). A 'cut-off' Hb level of 112 g/L was identified by ROC analysis. Conclusions: Preoperative anemia in infrainguinal bypass surgery has a significant association with mortality and morbidity. Preoperative anemia should prompt the vascular team to consider these patients as high risk and consider optimization of Hb.