Study Identifies Risk Factors for Vascular Graft Infections

Factors such as long procedure time, inadequate perioperative antimicrobial prophylaxis, and postoperative complications contribute to the risk of developing vascular graft infections, according to the results of a new study published online October 15 in the journal Clinical Infectious Diseases.

“While the former 2 cannot be substantially influenced, perioperative prophylaxis, as well as a thorough postsurgical management, could be key vascular graft infection prevention strategies,” wrote Alexia Anagnostopoulos, MD, MPH, from the University Hospital Zurich, Switzerland, and colleagues.

Vascular graft infections are serious complications of reconstructive vascular surgery that may increase patients’ morbidity and mortality. Several factors have been reported to increase the risk for these infections, including groin incision, wound infections, and comorbidities such as congestive heart failure.

However, most studies investigating these risk factors have been retrospective. With this in mind, Dr. Anagnostopoulos and colleagues aimed to prospectively evaluate incident vascular graft infection, and identify potentially avoidable risk factors to help guide development of infection prevention strategies.

They conducted their study in 438 participants in the prospective Vascular Graft Infection Cohort (VASGRA) study who underwent 768 surgical procedures between 2013 and 2017, contributing to 554 person-years of follow-up (PYFU).

According to the researchers, 39 (8.9%) developed a vascular graft infection, corresponding to an incidence rate of 7.0/100 PY (95% CI, 5.1 - 9.6).

After adjusting for variables such as age, gender, and body-mass index, Dr Anagnostopoulos and colleagues found that vascular graft infection was strongly associated with several patient- and procedure-related risk factors.

These were: incisional surgical site infections (adjusted hazard ratio [aHR], 10.09; 95% CI, 2.88 - 35.34); hemorrhage (aHR, 4.92; 95% CI, 1.28 - 18.94); renal insufficiency (aHR, 4.85; 95% CI, 1.20 - 19.61); inadequate perioperative prophylaxis in patients receiving antibiotics for another infection at the time of surgery compared to those receiving standard perioperative prophylaxis (aHR, 2.87; 95% CI, 1.17 - 7.05); and procedure time per 1-hour increase (aHR, 1.22; 95% CI, 1.08 - 1.39).

Comparing these findings with those of other studies is difficult, the authors wrote, because studies including suitable reference cohorts with prospective recruitment of patients with vascular graft infections and contemporary control patients are lacking.

However, they note that their findings are similar to those of 1 retrospective study that investigated risk factors for vascular graft infection. “Similar to our study, risk factors from different categories (host-, procedure-, and postoperative course-related) were evaluated, and SSI [surgical site infections] and wound complications after graft surgery were identified as important risk factors,” the authors write.

Although some of these risk factors can be influenced to only a limited extent, using perioperative prophylaxis is known to be protective in reducing the risk of SSI. Thus, perioperative prophylaxis, as well as its timeliness and adequacy, were considered key to reducing the risk for vascular graft infection.

“We found a benefit of timely dosing (less than 60 minutes prior to incision),” the authors say. “However, some of our patients were already under an established antibiotic therapy due to another infection at the time of index surgery. Compared to patients only receiving standard perioperative prophylaxis, these patients were at significant risk for vascular graft infection since in most cases, the perioperative antimicrobial management was inadequate.”

Dr Anagnostopoulos and colleagues emphasize that when patients are already receiving antibiotics for another infection at the time of surgery, physicians may mistakenly believe this coverage to be sufficient and thus avoid using perioperative prophylaxis.

Nevertheless, despite the need to provide adequate antimicrobial prophylaxis for these patients, the authors stress that physicians must also practice rational antibiotic prescribing, in particular, to pay careful consideration to the increasing rates of antibiotic-resistant infections and Clostridium difficile-associated colitis.

Dr. Parry, a board-certified veterinary pathologist, graduated from the University of Liverpool in 1997. After 13 years in academia, she founded Midwest Veterinary Pathology, LLC, where she now works as a private consultant. Dr. Parry writes regularly for veterinary organizations and publications.