Predictors of wound complications following major amputation for critical limb ischemia

Objectives: For patients with end-stage critical limb ischemia (CLI) who have already suffered over an extended period of time, a major amputation that is free of wound complications remains paramount. Utilizing data from the American College of Surgeons, National Surgical Quality Improvement Program (ACS-NSQIP), the objective of this report was to determine critical factors leading to wound complications following major amputation. Methods: ACS-NSQIP was used to identify patients <50 years, with CLI, and having an ipsilateral below-(BKA) or above-knee amputation (AKA). The primary outcome was wound occurrence (WO) defined by affirmative findings of superficial infection, deep infection, and/or wound disruption. The secondary outcome was 30-day mortality. Following univariate analyses, a multiple logistic regression was performed to identify predictive factors. Results: Between January 1, 2005 and December 31, 2008, 4250 patients fulfilled inclusion criteria (2309 BKAs and 1941 AKAs). WOs were 10.4% for BKAs and 7.2% for AKAs. For BKAs, increasing elevation in international normalized ratio (INR) predicted more WOs (P = .008, odds ratio [OR] 1.5 for every integral increase in INR) as did age 50 to 59 compared with older patients (P = .002, OR 1.9). For AKAs, being a current smoker predicted more WOs (P = .0008, OR 1.8) as did an increasing body mass index (BMI) (P = .02, OR 1.3 for every 10 kg/m ² increase in BMI). Mortality was 7.6% for BKAs and 12% for AKAs. Complete functional dependence was most predictive of mortality following AKA (P < .0001, OR 2.5). Medical comorbidities such as history of myocardial infarcation (MI) (OR 1.8), congestive heart failure (CHF, OR 1.6), and chronic obstructive pulmonary disease (COPD, OR 1.6) predicted mortality following BKA, while dialysis use (OR 2.4), CHF (OR 2.3), and COPD (OR 2.1) predicted mortality following AKA. Conclusions: Wound occurrences and mortality rates after major amputation for CLI continue to be a prevalent problem. Normalization of the INR prior to BKA should decrease WOs. Heightened awareness in higher risk patients with improved preventive measures, earlier disease recognition, better treatments, and increased education remain critical to improving outcomes in an already stressed patient cohort.