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Impact of foot infection on infrainguinal bypass outcomes in patients with limb-threatening ischemia
Wilmer Valentin, Joseph L. Mills, Neal R. Barshes, George Pisimisis, Jayer Chung, Panagiotis Kougias
Baylor college of medicine, Houston, TX

Background: Despite advances in endovascular therapy, infrainguinal bypass (IB) continues to play a major role in achieving limb salvage in the patients with extensive tissue loss and long segment occlusive disease. In this study we sought to compare the outcomes of 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, 6-month readmission, and postoperative length of stay. Limb-related endpoints included major amputation (transfemoral, transtibial, or through the knee), 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 group. 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 (table 2). 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 the presence of 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 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 additional support to the inclusion of infection in risk stratification schemes for patients with limb-threatening ischemia, as recommended in the Society for Vascular Surgery WIfI Classification System, because of its adverse impacts on limb salvage.
Significant predictors of mortality and major amputation among those undergoing infrainguinal bypass
VariableHazard ratio95% Confidence intervalp-value
Mortality
Age1.041.02, 1.07<0.001
Congestive heart failure2.061.26, 3.360.004
Albumin0.610.45, 0.820.001
Clopidogrel0.430.25, 0.740.003
Major amputation
Infection1.861.25, 2.780.002
Age0.960.93, 0.990.025
Body mass index0.940.91, 0.980.014

Statin1.921.14, 3.240.014
Significant predictors of post-operative length of stay among those undergoing infra-inguinal bypass.
VariableCoefficient95% Confidence intervalp-Value
Infection1.660.76, 2.55<0.001
Glomerular filtration rate-0.02-0.043, -0.014<0.001
Aspirin-1.16-2.13, -0.180.02
Albumin-1.35-2.11, -0.60<0.001
Redo-open1.360.49, 2.240.02
Operating room estimated blood loss0.0030.001, 0.004<0.001


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