Damian McNamara

October 26, 2016

LAS VEGAS — Rates of hospital admission and relapse related to Clostridium difficile infection are significantly higher after Roux-en-Y gastric bypass than after vertical sleeve gastrectomy or ventral hernia repair, according to findings from a study that won the 2016 Obesity Award.

An association "has been suggested" between obesity and C difficile infection, said Emmanuel Ugbarugba, MD, from the Ohio State University Wexner Medical Center in Columbus. "However, the impact of bariatric surgery — specifically Roux-en-Y gastric bypass surgery and vertical sleeve gastrectomy — has not been previously investigated."

Dr Ugbarugba presented "unexpected" findings from the study here at the American College of Gastroenterology 2016 Annual Scientific Meeting.

He and his team used the Nationwide Readmission Database to determine rates of C difficile infection in the 30 days after hospital admission and rates of relapse requiring hospitalization in the 120 days after surgery.

Their study involved 40,191 obese adults who underwent Roux-en-Y gastric bypass and 45,644 who underwent vertical sleeve gastrectomy in 2013. These patients — in the 90 days before surgery — served as a control population, as did 10,995 obese patients who underwent ventral hernia repair during the same period.

The risk for C difficile infection was higher after Roux-en-Y gastric bypass than after vertical sleeve gastrectomy from days 1 to 30 after the procedures (adjusted odds ratio [OR], 4.5) and from days 31 to 120 (OR, 9.8). Although rates of C difficile infection were similar between the Roux-en-Y gastric bypass group and the hernia surgery group from days 1 to 30, rates were higher after gastric bypass from days 31 to 120 (OR, 6.7).

Cause Debated

Session comoderator David Greenwald, MD, from the Mount Sinai Medical Center in New York City, asked Dr Ugbarugba to provide his "best guess" on the cause of these findings.

They might be related to a decrease in acid production associated with the surgery, Dr Ugbarugba suggested.

"It's very interesting. I see a lot of C difficile patients," said session comoderator Colleen Kelly, MD, from the Miriam Hospital in Providence, Rhode Island. The higher rate with gastric bypass than with other surgeries is "a very dramatic result."

She speculated that changes in distal gut bacteria after Roux-en-Y gastric bypass could cause an increase in C difficile infection.

After the presentation, a member of the audience asked about the clinical implications of the findings, given the low rates of C difficile infection after bypass surgery or gastrectomy.

The rate of C difficile infection is 66 per 100,000 per year in those younger than 65 years, Dr Ugbarugba reported. "For our patients, it was 174 per 100,000 in the 4 months after surgery, so it's more than twice the normal rate in the general population," he pointed out.

Study limitations include an inability to assess readmission for C difficile acquired during hospitalization, postsurgery C difficile infections treated in the outpatient setting, and the potential for confounding factors, such as the use of proton pump inhibitors, he acknowledged.

"Because it's a database study, we cannot confirm causality and can only suggest association," Dr Ugbarugba cautioned. "Further studies validating this risk, including mechanistic explanations, are warranted."

Dr Ugbarugba, Dr Greenwald, and Dr Kelly have disclosed no relevant financial relationships.

American College of Gastroenterology (ACG) 2016 Annual Scientific Meeting: Abstract 40. Presented October 18, 2016.

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