Preop Antibiotic Exposure, Surgical Complexity Up CDI Risk

Diana Swift

November 30, 2015

The 30-day postoperative rate of Clostridium difficile infection (CDI) was significantly associated with the number of antibiotic classes given in the 60 days before surgery and the complexity of the surgery, according to a study of almost 470,000 surgical procedures. The study was published online November 25 in JAMA Surgery.

Postoperative morbidity and mortality were increased 12-fold and fivefold, respectively, in patients with postoperative CDI, compared with patients who did not develop the infection, the researchers write.

Significant risk factors for CDI were the number of antibiotic classes given within the 60 days before surgery, emergency procedures, complex surgeries, and those with intraoperative wounds classified as contaminated or infected, report biostatistician Xinli Li, PhD, from the National Surgery Office of the Veterans Health Administration in Washington, DC, and colleagues.

According to figures from 2009 to 2013 collected under the Veterans Affairs (VA) Surgical Quality Improvement Program, the CDI rate was 0.4% per year (range, 0.0% - 1.4%). There were 1833 cases of 30-day postoperative CDI: 1239 (67.6%) were diagnosed during initial hospitalization and others during readmission periods or outpatient procedures. The cases were documented in 12 noncardiac surgical specialties in 134 VA surgery facilities.

Compared with noninfected patients, those contracting a CDI had more than 12 times the rate of postoperative morbidity (86.0% vs 7.1%; P < .001). They also had a fivefold greater risk of dying within 30 days of surgery (5.3% vs 1.0%; P < .001), as well as almost five times longer mean postoperative hospital stays (17.9 days vs 3.6 days; P < .001).

The highest CDI rate occurred in organ transplants at 2.37% (2.6% for kidney and 3.1% for lung transplants). Next-highest rates occurred with emergency procedures, at 1.43%, and those with infected (1.41%) or contaminated (1.28%) intraoperative wounds. The lowest rates occurred in oral surgery (0.00%) and gynecologic procedures (0.06%).

Compared with noninfected patients, those with postoperative CDI were older (mean age, 67.4 vs 60.6 years; P < .001) and frailer and had been treated with at least three different classes of antibiotics (1.5% vs 0.3% for a single class; P < .001) within 60 days before surgery.

Patients with CDI suffered more frequent 30-day postoperative morbidities, including cardiac and pulmonary complications, central nervous system events, renal impairment, and surgical site infections.

The median time to postoperative CDI infection was 9 days, but it varied among specialties. Over the course of 4 years, infection rates also varied between different centers, from 0% to 1.4%, and were likely to remain high at centers with initially high rates and low at centers with initially low rates. "[T]his VA facility variance is likely owing to the case mix of patients and the complexity of the surgical procedures performed," the researchers write. "However, medical practice may also play a significant role in CDI."

They add that their findings might aid administrators and clinicians in developing interventions for at-risk patients undergoing high-risk procedures, thereby reducing the CDI rate. They suggest such preventive measures as selective use of antibiotics, early testing of vulnerable patients, hand washing with nonalcohol agents, and special environmental cleaning protocols.

In an accompanying commentary, Paul K. Waltz, MD, and Brian S. Zuckerbraun, MD, from the VA Pittsburgh Healthcare System in Pennsylvania, stress the significant increases in morbidity and mortality associated with CDI. They suggest that CDI patients may have compromised immune responses and are therefore vulnerable to other hospital-acquired infections as well.

"Taken together, this article adds to our understanding of CDI and underscores the importance of infection control and prevention strategies, including antibiotic stewardship," Dr Waltz and Dr Zuckerbraun write. They add that the results underscore "the importance of the development of prophylactic strategies, expeditious recognition of CDI, adequate supportive care, and improved therapies."

They caution, however, that this study may not have captured all cases of postoperative CDI, as some may have been diagnosed outside the VA system. Furthermore, they note, hospital-acquired CDI is usually considered to occur within the 3 months after hospitalization, whereas this study focused only on the 30-day postoperative period. "Additionally, given the approximately 20% recurrence rate of CDI, inclusion of this end point would add further strength to this study," they write.

The study authors and the commentators have disclosed no relevant financial relationships.

JAMA Surg. Published online November 25, 2015. Abstract, Commentary

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