To Örebro University

BACKGROUND: The association between bariatric surgery and new onset of inflammatory bowel disease has so far only been sparsely studied and with conflicting results.

OBJECTIVES: To investigate the association between bariatric surgery and inflammatory bowel disease in a large population-based cohort.

SETTING: Nationwide in Sweden.

METHODS: This population-based retrospective cohort study included Swedish individuals registered in the Scandinavian Obesity Surgery Registry who underwent primary Roux-en-Y gastric bypass or sleeve gastrectomy during 2007-2018. Ten control individuals from the general population were matched according to age, sex, and region of residence at time of exposure. The study population was followed until 2019 with regard to the development of inflammatory bowel disease. Cox proportional hazards models were used to compare disease-free survival time between subgroups and control individuals for each outcome.

RESULTS: The final cohort consisted of 64,188 exposed individuals with a total follow-up of 346,860 person-years and 634,530 controls with total follow-up of 3,444,186 person-years. Individuals who underwent Roux-en-Y-gastric bypass had an increased risk of later development of Crohn's disease (hazard ratio [HR] 1.8, 95% CI 1.5-2.2) and unclassified inflammatory bowel disease (HR 2.7, 95% CI 2.0-3.7) but not ulcerative colitis (HR .9, 95% CI .8-1.1) compared with control individuals, whereas individuals who underwent sleeve gastrectomy had an increased risk of ulcerative colitis (HR 1.8, 95% CI 1.1-3.1) but not Crohn's disease (HR .8, 95% CI .3-2.1) and unclassified inflammatory bowel disease (HR 2.5, 95% CI .8-7.8).

CONCLUSIONS: Roux-en-Y gastric bypass was associated with increased risk of Crohn's disease and unclassified inflammatory bowel disease, whereas sleeve gastrectomy was associated with increased risk of ulcerative colitis only.