Predictors of surgical site infection after hospital discharge in patients undergoing major vascular surgery

Abstract

Objective Surgical site infection (SSI) is one of the most common post-operative complications following vascular reconstruction, producing significant morbidity and hospital readmission. In contrast to SSI that develops while patients are still hospitalized, little is known about the cohort of patients that develop SSI following discharge. In this study, we explore the factors that lead to post-discharge SSI, investigate the differences between risk factors for in-hospital versus post-discharge SSI, and develop a scoring system to identify patients that might benefit from post-discharge monitoring of their wounds. Methods Patients who underwent major vascular surgery from 2005–2012 for aneurysm and lower extremity occlusive disease were identified from the American College of Surgeons National Surgical Quality Improvement Program Participant Use Files. Patients were categorized as having no SSI, in-hospital SSI, or SSI after hospital discharge. Predictors of post-discharge SSI were determined by multivariable logistic regression and internally validated by bootstrap resampling. Risk scores were assigned to all significant variables in the model. Summative risk scores were collapsed into quartile-based ordinal categories and defined as low-, low/moderate-, moderate/high-, and high-risk. Multivariable logistic regression was used to determine predictors of in-hospital SSI. Results Of the 49,817 patients who underwent major vascular surgery, 4,449 (8.9%) were diagnosed with SSI (2.1% in-hospital; 6.9% post-discharge). By multivariable analysis, factors significantly associated with increased odds of post-discharge SSI include female gender, obesity, diabetes, smoking, hypertension, coronary artery disease, critical limb ischemia, chronic obstructive pulmonary disease, dyspnea, neurological disease, prolonged operative time >4 hours, American Society of Anesthesiology classification IV or V, lower extremity revascularization or aortoiliac procedure, and groin anastomosis. The model exhibited moderate discrimination (bias-corrected c-statistic, 0.691) and excellent internal calibration. The post-discharge SSI rate was 2.1% for low-risk patients, 5.1% for low/moderate-risk patients, 7.8% for moderate/high risk patients, and 14% for high-risk patients. In a comparative analysis, comorbidities were the primary driver of post-discharge SSI whereas in-hospital factors (operative time, emergency case status) and complications predicted in-hospital SSI. Conclusions The majority of SSIs after major vascular surgery develop following hospital discharge. We have created a scoring system that can select a cohort of patients at high-risk for SSI following discharge. These patients can be targeted for transitional care efforts focused on early detection and treatment with the goal of reducing morbidity and preventing readmission secondary to SSI.

Risk Factors for 30-Day Hospital Re-Admission with an Infectious Complication after Lower-Extremity Vascular Procedures

“…We found that among patients re-admitted with an infection, surgical site infection and LE cellulitis were the most common. This is similar to previous reports that have identified surgical site complications, including infections, as the most common reason for readmission [11,12]. Engelbert et al evaluated more than 2,000 patients from a single institution and found that surgical site complications were the most common re-admitting diagnosis, with site infection accounting for 20% of the re-admissions [10].…”

“…Co-morbidities associated with re-admission and infection in bivariable analysis included a diagnosis of diabetes at the time of the index procedure. Previous investigations have supported this conclusion indirectly by demonstrating a direct association between insulindependent diabetes and a higher risk of 30-d re-admission [4,12,22]. Although the association between diabetes and re-admission is not surprising, it may well represent an association between poor glucose control and an overall higher risk of infection.…”

Inter-rater agreement and checklist validation for postoperative wound assessment using smartphone images in vascular surgery

“…However, it may also best represent the surgical population as a whole as this population frequently develops SSI, 35 and has the highest readmission rate among surgical specialties. 10–12 In addition, we did not undertake any post hoc adjustment of the images' color balance, although the presence of the ruler in each image enables this.…”

Role of Antibiotic Prophylaxis in Elective Mesh Inguinal Hernioplasty

“…The grade of the surgeon was not a statistically significant risk factor for SSI in our study. Taylor et al 13 in their study concluded that the grade of the surgeon does not influence the rate of SSI in groin hernia repair. Aufenacker et al 5 also reported similar results from their study.…”