Our group published a similar article in the Journal of Crohn’s and Colitis prior to this publication.

We conducted a two-center study at Mayo Clinic, Rochester, Minn., and Washington University in St. Louis, Mo., where we identified 44 patients with de novo inflammatory bowel disease (IBD) after bariatric surgery (31 Crohn’s disease, 12 UC, 1 IBD unclassified). Most patients were women (88.6%), and had a median age at IBD onset of 44 years (Interquartile range [IQR], 37–52) and median time to IBD diagnosis after bariatric surgery of 7 years (IQR, 3–10). Sixty-eight percent underwent Roux-en-Y gastric bypass.

We further looked at the incidence of IBD in patients who underwent bariatric surgery in a prospective database of bariatric surgery patients maintained at the Mayo Clinic where this was noted to be 26.7 per 100,000 person-years (4.5 for UC and 22.3 for Crohn’s disease). The age-adjusted standardized incidence ratio (SIR) ranged from 3.56 in the age 40 to 49 years group to 4.73 in the age 30 to 39 years group.

This study by Ungaro et al. and our study suggest that IBD should be considered in the differential diagnosis of delayed onset of worsening diarrhea or new/worsening abdominal pain in patients with a history of bariatric surgery. The reasons for the increased risk for IBD may be due to changes in microbiome although that is speculative and needs to be proven in prospective studies in patients undergoing bariatric surgery and followed over time.

The second factor here could be obesity. Obesity is considered a chronic low-grade inflammatory process mediated by pro-inflammatory cytokines, such as TNF-alpha and interleukin-6, as well as adipokines such as leptin and resistin secreted by adipocytes or macrophages. Although obesity has been associated with increased disease activity of several autoimmune conditions such as rheumatoid arthritis and psoriasis, this association has not been consistently demonstrated in IBD. Finally, despite this association with IBD, bariatric surgery remains a safe and reliable option for significant weight loss especially in medically complicated obesity.

Reference:

Braga Neto MB, et al. J Crohn’s Colitis. 2017;doi:10.1093/ecco-jcc/jjx177.

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.

References:

Bedard NA, et al. Clin Orthop Relat Res. 2018 Jan;476(1):52-63.

Braga Neto MB, et al. J Crohns Colitis. 2017;doi:10.1093/ecco-jcc/jjx177.

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