Bariatric surgery is effective at reducing weight and metabolic disease in patients with obesity. Concerns remain about long-term adverse events, reported to occur in 17% to 40% of patients. Two recent studies, one from Mayo Clinic and one from the New York Crohn’s and Colitis Organization (NYCCO) and collaborators, describe possible association of bariatric surgery and an increased incidence of inflammatory bowel disease (IBD).
In the latter study by Ungaro et al, six medical centers including three in New York, and three in Europe, reviewed their health records to identify patients with a new diagnosis of IBD after bariatric surgery. The study authors also queried a large insurance claims database of 190 million patient records, for incidence of IBD and past history of bariatric surgery. Intriguingly, bariatric surgery performed more than 4 years prior was associated with increased risk for new-onset IBD (OR = 1.79; 95% CI, 1.24-2.6), while controlling for age, obesity, cholecystectomy, and other relevant confounders.
Some potential mechanisms may be related to alteration of gut anatomy with resultant dysbiosis. In fact, studies have shown some alterations in gut bacteria after Roux-en-Y gastric bypass that resemble those of patients with IBD. Other possible contributors may be malabsorption of certain micronutrients, such as vitamin D, which is often present both before and after bariatric surgery, and which has also been linked to IBD development and disease activity. While the etiology of IBD is still unclear, the study results do suggest that changes in the intestinal environment, such as the gut microbiome, may drive disease rather than merely being a secondary effect of IBD development. However, direct cause-effect relationship between bariatric surgery and IBD has not been established.
The reader should interpret with caution findings from retrospective analysis of large databases. For example, obesity is a risk factor for total knee arthroplasty; however, claims are rarely submitted with this diagnosis. Most patients with history of bariatric surgery would still meet criteria for obesity, but the diagnosis may not have been used in claims. A surgical procedure is much more likely to be coded. Thus, it may be obesity actually driving the new incidence of IBD in the bariatric surgery cohort, or weight regain after bariatric surgery leading to obesity. Until more prospective data are available, we would advise our patients with obesity to lose weight by guidelines, and FDA-approved methods if they want to decrease their future risk for IBD. But we will inform patients planning bariatric surgery who have risk factors for IBD about the results of this very relevant study
Lea Ann Chen, MD, of the division of gastroenterology at NYU Langone, contributed to this perspective.
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Violeta Popov, MD, PhD
Director of Bariatric Endoscopy,
NY VA Harbor Healthcare(Manhattan)
Assistant Professor of Medicine,
NYU School of Medicine
Disclosures: Popov reports no relevant financial disclosures. Chen, who contributed to this perspective, was a co-author on the original paper.