Predictors of Surgical Site Infection Following Infra-Inguinal Bypass Surgery: An Analysis of the Vascular Quality Initiative Data.

Objective: Surgical site infection (SSI) is a common complication following infra-inguinal bypass (IIB) in patients with peripheral artery disease (PAD), leading to significant morbidity, including prolonged hospital stays, increased readmission rates, graft failure, and mortality. Despite advances in aseptic techniques, SSI continues to impact patient outcomes, driven by a complex interplay of patient-specific and procedural factors. This study aims to identify predictors of postoperative SSI in patients undergoing IIB providing insights into potentially modifiable risk factors.

Methods: We performed a retrospective analysis of all patients undergoing IIB for PAD in the Vascular Quality Initiative (VQI) database from 2010-2024. Patients with concomitant ipsilateral major amputation, supra-inguinal bypass, acute limb ischemia, or aneurysmal disease were excluded. Multivariable logistic regression was used to identify risk factors associated with postoperative SSI.

Results: Of 59,221 patients undergoing IIB, 1,857 (3.1%) developed SSI. Patients with SSI were more likely to be female, obese, have CKD or CHF. Urgent procedures, longer operative times, intraoperative blood transfusions, autogenous grafts, and below-knee bypasses were also more common in the SSI group. Multivariable analysis identified several significant predictors of SSI. Among patient factors, non-U.S. insurance (OR:2.84,95%CI:1.43-5.65,P=0.003) and obesity (Body Mass Index (BMI) 25-29.9:OR:1.43,95%CI:1.09-1.88,P=0.01; BMI 30-40:OR:1.64,95%CI:1.21-2.21,P<0.001; BMI ≥40:OR:2.22,95%CI:1.57-3.13,P<0.001) were associated with an increased risk of SSI. Rest pain (OR:1.23,95%CI:1.01-1.49,P=0.04) and tissue loss (OR:1.67,95%CI:1.38-2.03,P<0.001) were also associated with increased risks of SSI. Comorbidities, including untreated COPD (OR:1.21,95%CI:1.01-1.44,P=0.04), severe CHF (OR:1.89,95%CI:1.13-3.14,P=0.01), untreated diabetes mellitus (DM) (OR:1.32,95%CI:1.02-1.70,P=0.03), and ESRD (OR:1.83,95%CI:1.01-3.33,P=0.046) were significantly associated with SSI. Perioperative factors such as intraoperative blood transfusion (OR:2.28,95%CI:2.00-2.59,P<0.001), prolonged operative time ≥150 minutes (OR:1.51,95%CI:1.20-1.89,P<0.001) and ≥300 minutes (OR:1.95,95%CI:1.50-2.54,P<0.001) increased the risk of SSI. Protective factors included medication controlled DM (OR:0.75,95%CI:0.58-0.97,P<0.03), preoperative antibiotics (OR:0.74,95%CI:0.64-0.85,P<0.001), prosthetic grafts (OR:0.85,95%CI:0.74-0.99,P=0.03), and using chlorhexidine(CHG) or iodine alone vs CHG-iodine combined for skin prep (CHG:OR:0.49,95%CI:0.34-0.69,P<0.001; iodine:OR:0.52,95%CI:0.33-0.84,P=0.007).

Conclusion: This study confirms several risk factors for SSI including increased SSI risk with higher BMI, COPD, CHF, untreated DM, rest pain or tissue loss presentation, intraoperative blood transfusion and prolonged operative time. Protective factors, including preoperative antibiotic use, and medication-controlled DM and HTN underscore the importance of optimizing perioperative care to reduce SSI risk. These findings highlight opportunities for targeted interventions and personalized risk stratification to reduce SSI and improve patient outcomes.