Risk of De-novo Inflammatory Bowel Disease Among Obese Patients Treated With Bariatric Surgery or Weight Loss Medications

Gursimran S. Kochhar; Aakash Desai; Aslam Syed; Abhinav Grover; Sandra El Hachem; Heitham Abdul-Baki; Preethi Chintamaneni; Elie Aoun; Sowjanya Kanna; Dalbir S. Sandhu; Siddharth Singh; Bo Shen; Edward V. Loftus Jr; Parambir S. Dulai


Aliment Pharmacol Ther. 2020;51(11):1067-1075. 

In This Article

Abstract and Introduction


Background: An association between bariatric surgery and development of de-novo inflammatory bowel disease (IBD) has been observed.

Aim: To evaluate further the association among bariatric surgery, weight loss medications, obesity and new-onset IBD.

Methods: Using Explorys, a population-based Health Insurance Portability and Accountability Act compliant database, we estimated the prevalence of de-novo IBD among patients treated with bariatric surgery (Roux-en-Y gastrojejunostomy, laparoscopic sleeve gastrectomy or gastric banding) (n = 60 870) or weight loss medications (orlistat, phentermine/topiramate, lorcaserin, bupropion/naltrexone and liraglutide) (n = 193 790) compared with obese controls (n = 5 021 210), between 1999 and 2018.

Results: The prevalence of de-novo IBD was lower among obese patients exposed to bariatric surgery (7.72 per 1000 patients) or weight loss medications (7.22 per 1000 patients) compared with patients with persistent obesity not exposed to these interventions (11.66 per 1000 patients, P < 0.0001). The risk reduction for de-novo IBD was consistent across bariatric surgeries and weight loss medications with the exception of orlistat which was not associated with a reduction in risk for de-novo IBD compared with the persistent obese control cohort.

Conclusion: Obese patients undergoing treatment with bariatric surgery or weight loss medications are at a lower risk for developing de-novo IBD compared with persistently obese controls not exposed to these interventions. These data suggest that obesity and ineffective management of obesity are risk factors for de-novo IBD. Further research is needed to confirm these observations and understand potential mechanisms.


Obesity is a rapidly growing healthcare concern, with more than 1.9 billion adults being classified as overweight (defined by the World Health Organization as having a body mass index (BMI) greater than or equal to 25 kg/m2), of whom over 650 million are obese (defined as having a BMI greater than or equal to 30 kg/m2).[1,2] Obesity treatment options include lifestyle modification, weight loss pharmacotherapy and bariatric surgery like Roux-en-y gastric bypass (RYGB).[3–8] Although effective, these treatment options can be associated with a risk for longer-term complications such as nutritional deficiencies. More recently, a greater deal of attention has been paid to the impact of bariatric surgeries on the microbiome, immune system and potential risk for immune-related diseases.[9,10]

A potential association between bariatric surgery and the development of de-novo inflammatory bowel disease (IBD) has been suggested. Braga Neto et al reported on a case series of 44 patients with de-novo IBD after bariatric surgery, where they observed an age-adjusted standardised incidence ratio of >3 for adults 30–49 years of age, and it was observed that a higher proportion of these de-novo IBD cases had Crohn's disease (CD) as compared with ulcerative colitis (UC).[11] Using national claims data, Ungaro and colleagues observed that a past history of bariatric surgery was associated with an increased risk for de-novo IBD (odds ratio [OR], 1.93), whereas a more recent history of bariatric surgery was not (OR, 0.94).[12] Within both studies several limitations remain which preclude our ability to know with certainty that bariatric surgery in itself is a risk factor for de-novo IBD. First, fewer than 100 cases have been reported between both studies combined, which create uncertainties due to sample size. Second, no prior studies have used active control comparator groups to help understand if obesity is a potential determinant of these de-novo IBD cases.[13] Ungaro et al observed that the average BMI of those patients who developed de-novo IBD after bariatric surgery was 30.8 kg/m2 at the time of IBD diagnosis, suggesting that the increased risk of IBD after bariatric surgery with remote surgery but not recent surgery may be a function of weight regain and some degree of confounding might exist.[12] Third, the follow-up period and ascertainment of claims analyses spanning a 4-year period is limited by patient drop-out or transitions in insurance coverage. Finally, it remains unclear if the potential association between bariatric surgery and IBD is secondary to altered anatomy and microbiome or effects of weight loss itself, and no prior studies have evaluated the risk of de-novo IBD among obese individuals treated with pharmacotherapy for weight loss.

To address these limitations and better understand the potential association between bariatric surgery and de-novo IBD, we performed an electronic medical record (EMR)-based analysis to compare the rates of de-novo IBD among obese individuals treated with bariatric surgery or pharmacotherapy for weight loss to those observed among obese individuals not exposed to these interventions. Results were further stratified by response to obesity treatments to understand how changes in BMI and persistence in obesity influence the risk of de-novo IBD.