The impact of foot infection on infrainguinal bypass outcomes in patients with chronic limb-threatening ischemia.

BACKGROUND: Despite advances in endovascular therapy, infrainguinal bypass continues to play a major role in achieving limb salvage. In this study, we sought to compare outcomes of infrainguinal bypass in patients with limb-threatening ischemia who presented with or without foot infection.

METHODS: We conducted a retrospective cohort study of patients who underwent infrainguinal bypass for chronic limb-threatening ischemia at a single institution. End points of interest included long-term mortality, 45-day readmission, postoperative length of stay (LOS), major amputation, and time to wound healing. Multivariable Cox, logistic, and robust regressions were used to model time to event outcomes, readmission rates, and LOS.

RESULTS: There were 454 infrainguinal bypass procedures analyzed. Demographics and baseline characteristics were similar, except congestive heart failure and diabetes were more common in the infection group. Presence of foot infection had no impact on mortality (hazard ratio [HR], 0.78; P = .243). Significant predictors of long-term mortality included increasing age, hypoalbuminemia, and congestive heart failure; preoperative use of clopidogrel was protective. Presence of foot infection was an independent predictor of major amputation. In the multiple regression model, the presence of foot infection was independently associated with amputation rate (HR, 2.14; 95% confidence interval, 1.42-3.22; P < .001); use of venous conduit and increasing age and body mass index were protective. Foot infection was an independent predictor of prolonged LOS (mean LOS was 1.54 days longer in patients with vs those without infection; P = .001). Other independent predictors of prolonged LOS included intraoperative blood loss and reoperation; history of continuous preoperative aspirin use and normal baseline renal function and albumin levels were associated with decreased LOS. Readmission was influenced by reoperation (odds ratio [OR], 2.51; P < .001) but not by presence of foot infection (OR, 1.21; P = .349). There was a strong trend for prolonged wound healing time in patients with diabetes (HR, 1.58; P = .05) but not in those with foot infection (OR, 0.74; P = .36).

CONCLUSIONS: Among patients requiring infrainguinal bypass for limb-threatening ischemia, infection was more common in patients with diabetes and was a significant predictor of major amputation and prolonged LOS. Infection was not predictive of mortality, wound healing time, or readmission. These findings lend support to the inclusion of infection in risk stratification schemes for patients with chronic limb-threatening ischemia, as recommended in the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system, because of its adverse impacts on limb salvage.