Lower Extremity Amputation Risk Factors Associated With Elevated Ankle Brachial Indices and Radiographic Arterial Calcification

Abstract

An elevated ankle brachial index (ABI) resulting from medial artery calcification, or Mönckeberg’s arteriosclerosis, is commonly seen in patients with diabetes mellitus or end-stage renal disease. Recent data have found an association between elevated ABIs and cardiovascular morbidity and mortality. The purpose of the present study was to evaluate the prognostic significance of high ABIs, poorly compressible arteries, and radiographic artery calcification compared with low ABIs in predicting lower extremity amputation and morbidity. A retrospective review was conducted of patients who had undergone a lower extremity amputation from July 1, 2011 to August 31, 2012. A total of 129 patients (140 lower extremity amputations) were categorized into 3 groups: a low ABI (<0.9), a normal ABI (0.9 to 1.3), and a high ABI (>1.3) or poorly compressible arteries. Of the 129 patients, 31 (22.14%), 36 (25.71%), and 73 (52.14%) were in group 1, 2, and 3, respectively. The prevalence of diabetes was greatest in group 2 (p = .016). A high percentage of radiographic arterial calcification was found in all 3 groups (p = .003). Statistically significant differences were also found in groups 1 and 3 for peripheral arterial disease (p < .001), chronic kidney disease (p < .001), coronary artery disease (p = .021), revascularization history (p < .001), and tobacco use (p = .012). A U-shaped relationship between the ABI and comorbidity was found, suggesting an elevated ABI is as equally prognostic as a low index in predicting the need for amputation.