Periprocedural Hemoglobin Levels Affect Amputation Rates in Patients Undergoing Interventions for Critical Limb Ischemia

Abstract

Critical limb-threatening ischemia (CLTI) of the lower extremity is associated with high rates of morbidity, including amputation and death. Unfortunately, there is a paucity of data related to how periprocedural metrics affect the success of these interventions for CLTI. Perioperative anemia has been shown to affect outcomes in patients suffering from myocardial ischemia. It can be postulated that the same physiologic principles can be applied to CLTI. We hypothesize that perioperative anemia may contribute to a higher risk for amputation in patients receiving interventions for CLTI. We performed a single-center, retrospective cohort study of patients undergoing procedures for CLTI at The Ohio State University Wexner Medical Center. Patients aged 18 to 100 years with International Classification of Diseases, Ninth Revision or Tenth Revision coding for CLTI of the lower extremities were included. Patients with interventions for claudication or acute limb ischemia were excluded. Demographic data and hemoglobin levels before intervention were obtained. The primary outcome was amputation of the affected limb after intervention. Secondary outcomes included the need for reintervention, 30-day mortality, and 30-day major complication rate. Statistical analyses using univariate and multivariate analysis with logistic regression models were performed to compare amputation rates with these variables. We identified 258 patients undergoing interventions for CLTI between 2006 and 2018. Fifty-nine (22.9%) went on to amputation. Multivariate analysis revealed that patients with hemoglobin levels of <12 g/dL had increased risk of amputation (odds ratio [OR], 2.57; confidence interval [CI], 1.12-5.85; P = .0003). In addition, age >80 years (OR, 0.228; CI, 0.060-0.871; P = .031), nonwhite race (OR, 2.83; CI, 1.32-6.05; P = .007), and male sex (OR, 3.4; CI, 1.61-7.24; P = .001) were identified as risk factors for amputation. Patients without preoperative antiplatelet therapy also had increased risk (OR, 0.31; CI, 0.133-0.697; P = .005). In this study, we showed that periprocedural hemoglobin levels below normal were an independent risk factor for amputation in our cohort of patients. Further prospective studies are indicated to identify whether hemoglobin should be a targeted, adjustable risk factor in patients undergoing interventions for CLTI.