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Objective: This study sought to compare the outcomes of infrainguinal bypass (IB) in patients with limb-threatening ischemia who presented with or without foot infection.
Methods: We conducted a retrospective cohort study of patients who underwent IB for limb-threatening ischemia at a single institution. Patient-related endpoints of interest included long-term mortality and postoperative length of stay. Limb-related endpoints included major amputation, and time to wound healing. Multivariable Cox, logistic, and robust regression were used to model time to event outcomes, readmission rates, and LOS respectively.
Results: Overall, 454 IB procedures that occurred over a 7-year period were analyzed. Demographics and baseline patient characteristics were similar between the infection and non-infection group, except congestive heart failure and diabetes were more common in the infection arm. Presence of foot infection had no impact on mortality (HR: 0.72, p = 0.113). Statistically significant predictors of long-term mortality included increasing age, hypoalbuminemia, and congestive heart failure, whereas preoperative use of Clopidogrel was protective (table 1). Presence of foot infection was an independent predictor of major ipsilateral amputation (HR: 1.86, p = 0.002). Other significant predictors of major amputation on multivariable analysis included history of statin administration, decreasing age, and low body mass index (table 1). In addition, foot infection was an independent predictor of prolonged LOS (mean LOS was 1.7 days longer in patients with versus those without infection, p < 0.001). Other independent predictors of prolonged LOS included intraoperative blood loss and reoperation in the index extremity; whereas history of continuous preoperative aspirin use, normal renal function and normal albumin levels were associated with decreased LOS. Readmission was influenced by the performance of a reoperation in the index extremity (OR: 2.57, p < 0.001) and history of diabetes (OR: 1.5, p = 0.023) but not foot infection (OR: 1.27, p = 0.192). There was a strong trend for prolonged wound healing time in patients with diabetes (HR: 1.57, p = 0.05), but not in those with foot infection (OR: 0.73 p = 0.36).
Conclusion: Among patients requiring infrainguinal bypass for limb-threatening ischemia, infection was a significant predictor of major amputation and prolonged LOS.

Significant predictors of mortality and major amputation among those undergoing infrainguinal bypass

Variable	Hazard ratio	95% Confidence interval	p-value
Mortality
Age	1.04	1.02, 1.07	<0.001
Congestive heart failure	2.06	1.26, 3.36	0.004
Albumin	0.61	0.45, 0.82	0.001
Clopidogrel	0.43	0.25, 0.74	0.003
Major amputation
Infection	1.86	1.25, 2.78	0.002
Age	0.96	0.93, 0.99	0.025
Body mass index	0.94	0.91, 0.98	0.014