Postcolonoscopy Antibiotics Linked With IBS

Will Pass

June 01, 2020

Antibiotic exposure within 14 days after screening colonoscopy may increase risk of irritable bowel syndrome (IBS), based on a retrospective analysis of more than 400,000 individuals.

Antibiotic use in the 2 weeks leading up to colonoscopy also trended toward an association with IBS, reported lead author Ravy Vajravelu, MD, of University of Pennsylvania, Philadelphia, and colleagues.

"Laboratory studies in mice have demonstrated that colon cleansing in conjunction with systemic antibiotic use can cause persistent intestinal dysbiosis," the investigators wrote in an abstract released as part of the annual Digestive Disease Week®, which was canceled because of COVID-19. "Because perturbation of the gut microbiome is thought to be a trigger for the development of IBS, we sought to assess whether humans who undergo bowel cleanse for colonoscopy in conjunction with antibiotic exposure develop new-onset IBS or IBS-related symptoms."

According to Dr. Vajravelu, previous human studies have shown that bowel cleansing or antibiotics can alter the baseline gut microbiome, but no previous human research explored the impact of both triggers at once.

The present study involved individuals 50 years or older from the OptumInsight Clinformatics database who underwent screening colonoscopy between 2000 and 2016. Those with preexisting gastrointestinal conditions or symptoms within 180 days leading up to colonoscopy were excluded, leaving 402,259 individuals in the final cohort. From this group, individuals were identified who had exposure to antibiotics within 14 days before and/or after colonoscopy.

The primary outcome was a diagnosis of IBS in the 180 days following the antibiotic exposure window. Secondary outcomes included newly diagnosed diarrhea, change in bowel habits, and abdominal pain. A variety of covariates were tested through multivariable logistical regression, including gastrointestinal infections, medical comorbidities, and demographic factors, with only sex and age remaining in the final model.

Across the cohort, 2% of patients received antibiotics either before or after colonoscopy, while 1% had exposure both before and after. A total of 1,002 individuals (0.2%) were diagnosed with IBS within a median time frame of 112 days.

Multivariate analysis revealed that individuals exposed to antibiotics in the 14 days following colonoscopy had a 77% increased risk of developing IBS (adjusted odds ratio, 1.77; 95% confidence interval, 1.31-2.39). To a lesser degree, and not quite achieving statistical significance, trends toward an association were found for antibiotic exposure before colonoscopy (aOR, 1.38; 95% CI, 0.99-1.92), and for antibiotic exposure both before and after colonoscopy (aOR, 1.41; 95% CI, 0.97-2.04).

Dr. Vajravelu said that these preliminary findings are currently undergoing further analysis.

"In particular, we are interested in determining whether antibiotics that target gram-negative bacteria, which are abundant in the gut, have a greater association with subsequent IBS," Dr. Vajravelu said.

In addition, they are taking steps to eliminate other confounding factors.

"The main objective of these new analyses is to ensure that the association between bowel cleanse and antibiotics with subsequent IBS is not related to the reasons antibiotics were prescribed initially," Dr. Vajravelu said. "For example, someone experiencing diarrhea could receive a trial of empiric antibiotics and then receive a colonoscopy when the diarrhea does not resolve. In [the present analysis], we avoided including individuals like this by including only those who underwent screening colonoscopy, and therefore did not have any prior documented GI symptoms. In our [ongoing] analyses, we are including additional restrictions to strengthen the findings."

If the findings do hold, Dr. Vajravelu suggested that they may have clinical implications.

"[I]t may be important to review whether patients scheduled for colonoscopy have received recent antibiotics and warn them to avoid antibiotics after colonoscopy, if possible," Dr. Vajravelu said. "Additionally, for gastroenterologists, these data may underscore the importance of adhering to preprocedural antibiotic prophylaxis guidelines put forth by GI societies."The investigators disclosed relationships with Merck, Pfizer, Gilead, and others.

Digestive Disease Week (DDW) 2020: Abstract 404.

This article originally appeared on

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