November 25, 2015
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Postoperative C. difficile infection rate, risk factors identified in VHA

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In a Veterans Health Administration study, patients showed lower than expected rates of postoperative Clostridium difficile infection, further linked to the number and class of antibiotics given after surgery, length of stay before surgery, procedural factors, surgical program complexity and patient comorbidities.

“To our knowledge, no study has reported risk factors associated with CDI across a variety of surgical specialties in the [VHA], a predominantly male and elderly surgical population,” the researchers wrote. “The objectives of this study were to document the CDI incidence in the VHA over a 4-year period across different surgical procedures, identify the risk factors associated with CDI, and determine the impact of CDI on postoperative mortality, morbidity, and hospital length of stay.”

The researchers performed an operational retrospective cohort study from September 2014 to April 2015 using the linked Veterans Affairs Surgical Quality Improvement Program (VASQIP) database and the Decision Support System pharmacy database. VASQIP assessments from October 2009 through September 2013 were included, representing 134 VHA surgery programs and 12 noncardiac surgical specialties.

They identified 468,386 procedures, and the overall 30-day postoperative CDI rate was 0.4% per year, which “is low compared with previously published rates,” the researchers wrote. This rate varied by VHA Surgery Program, from 0% to 1.4%, and by surgical specialty, from 0% for oral surgeries to 2.37% for transplant surgeries.

The mean age of patients with postoperative CDI was significantly higher compared with patients without CDI (67.4 vs. 60.6 years; P < .001). Patients with postoperative CDI were also hospitalized more often after surgery (59.9% vs. 15.4%), had longer preoperative hospital stays (9.1 days vs. 1.9 days) and received three or more classes of antibiotics (1.5% vs. 0.3% for a single class; all P < .001).

Overall, 30-day CDI rates were significantly higher in emergency procedures compared with nonemergency procedures (1.43% vs. 0.34%), procedures with greater complexity and higher relative value units and those with contaminated and infected wound classifications (all P < .001).

Postoperative 30-day morbidity and mortality were found to be significantly higher for patients with postoperative CDI compared with those without CDI (86% vs. 7.1% and 5.29% vs. 1.02%, respectively; both P < .001). Postoperative hospital stays were also longer among patients with postoperative CDI (17.9 vs. 3.6 days; P < .001).

Multivariate regression analysis showed independent predictors of CDI included “commonly identified patient factors (albumin, functional class, and weight loss), procedural characteristics (complexity, relative value unit, emergency, and wound classification), surgical program complexity, the number of preoperative antibiotic classes, and length of preoperative hospital stay,” the researchers wrote. “Mitigation of these CDI risk factors has the potential to decrease the overall incidence of CDI.”

While these risk factors “were as expected,” a finding worthy of highlighting “is the 12-fold increase in morbidity and 5-fold increase in mortality associated with CDI compared with postoperative patients without CDI,” Paul K. Waltz, MD, and Brian S. Zuckerbraun, MD, from the VA Pittsburgh Healthcare System and the University of Pittsburgh, wrote in a related editorial. “While CDI can directly lead to clinical deterioration resulting in increased morbidity and mortality, this may also suggest that patients who develop CDI have an impaired immune response and are a vulnerable population for other hospital-acquired infections and poor outcomes.”

Overall, the study reinforces the importance of infection control and prevention, and supports “the development of prophylactic strategies, expeditious recognition of CDI, adequate supportive care, and improved therapies,” they concluded. – by Adam Leitenberger

Disclosures: The researchers, Waltz and Zuckerbraun report no relevant financial disclosures.