Post-endoscopic infection rates are higher than ‘1 in a million’

Although post-endoscopic infections after colonoscopy and osophagogastro-duodenoscopy (OGD) happen more often than experts previously imagined, the risk of such infections is still lower than those of other diagnostic endoscopic procedures such as cystoscopy and bronchoscopy, according to a new study published in Gut.

“No study has examined the rate of infections after colonoscopy or OGD,” wrote lead author Susan Hutfless, PhD, Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD. “In particular, no study or case report has examined rates of infections after screening colonoscopy, non-screening colonoscopy or OGD performed in ASCs [ambulatory surgery centers].”

Experts have recently recognized that mechanisms other than instrument design flaws may contribute to post-endoscopic infections, including health-care facility characteristics. Reforms in health care have moved more than 50% of endoscopies done in the United States to ASCs; however, no study has looked at infection levels due to screening colonoscopies, non-screening colonoscopies, or OGDs done is US ASCs.

Dr. Hutfless noted that post-endoscopic infection rates were previously believed to be roughly 1 in a million. She and her team found that the actual rates of infection are much higher.

For this study, the researchers assessed the variability of infection rates after screening colonoscopies (n=462,068), non-screening colonoscopies (n=914,140), and OGDs (n=873,138) done at ASCs in six states (representing 31% of US population) in 2014. They mined all-payer information and traced hospitalizations and emergency department visits within 7 and 30 days of endoscopic procedures. They also looked at predictors of infection.

The investigators chose screening mammography as a primary comparator. Because this procedure is noninvasive and usually performed on healthy patients, rates of infection in patients who receive screening mammography could provide background information on levels of infection in ASCs. The team also compared infection rates with bronchoscopy and cystoscopy, which are invasive, performed in ASCs, and require sedation.

Within 7 days of endoscopy, rates of infection were 1.1 per 1,000 procedures for screening colonoscopy, 1.6 per 1,000 for non-screening colonoscopy, and 3.0 per 1,000 for OGD (P < 0.0001). Comparatively, rates of infection were 0.6 per 1,000 for screening mammography, 15.6 per 1,000 for bronchoscopy, and 4.4 per 1,000 for cystoscopy (P < 0.0001).

The team found that 30-day infection rates after endoscopy were 4.0 per 1,000 for screening colonoscopy, 5.4 per 1,000 for non-screening colonoscopy, and 10.8 per 1,000 for OGD, compared with 2.9 per 1,000 for screening mammography.

Dr. Hutfless and colleagues found that certain factors predicted post-endoscopic infection in patients, including: recent history of hospitalization or endoscopic procedures; performance of another endoscopic procedure at the same time; low procedure volume or non-freestanding ASC; younger or older age; African American or Native American race; and male sex. 

The most common organisms implicated in post-endoscopic infections within 7 or 30 days were E. coli, C. difficile, and Staphylococci.

“The rate of post-endoscopic infections varies widely by ASC with a range of 0%–12.3% for screening colonoscopy, 0%–12.8% for non-screening colonoscopy, and 0%–4.7% for OGD,” the researchers wrote. “ASC annual procedure volume is the strongest facility factor associated with risk of infection with the lowest relative risk after procedures performed in high-volume ASCs.”

The researchers pointed out certain implications of their findings. For instance, these data could inform patient-provider communication regarding infection risk post-endoscopy. Additionally, procedure volumes and infection rates disclosed by ASCs and made available to patients could inform patient decision-making. Finally, providers could use these data to better time endoscopic procedures, and avoid such interventions among recently hospitalized patients.

“We found that post-endoscopic infections are more common than previously thought and vary widely by facility,” the researchers concluded. “Although screening colonoscopy is not without risk, the risk is lower than diagnostic endoscopic procedures.”

The study was funded by the US Department of Health and Human Services Agency for Healthcare Research and Quality.