Abstract Background The appendix is an immunologically active organ and can impact inflammatory bowel disease (IBD) risk. Recent trials have explored the role of appendectomy as a therapeutic strategy for ulcerative colitis (UC). However, the long-term impact of appendectomy on IBD outcomes are not known. Methods Using cross-linked registers, we identified a source population of all individuals living in Denmark between January 1, 1997, and December 31, 2024, with CD or UC diagnosis and no history of appendectomy. From this population, we identified all individuals with a diagnosis of appendectomy and matched each with 10 non-exposed individuals on date of appendectomy, age, time since diagnosis, IBD subtype, and sex. Using multi-factor adjusted Cox proportional hazards regression models, we determined the hazards of the composite outcome of systemic corticosteroid use, IBD-related hospitalizations, or IBD-related surgery. We assessed colorectal cancer risk as a secondary outcome. The follow up period extended from 6 months after the date of appendectomy or matching to first outcome, emigration, death, or December 31, 2024, whichever occurred first. Results Of 69,359 eligible individuals, we included 1,368 and 13,365 individuals with and without appendectomy following IBD diagnosis, respectively. The median (IQR) follow-up period was 7 years (3, 12). Baseline characteristics of the two groups were comparable with respect to demographic variables, calendar year at entry, family history of IBD, and municipality of residence. The hazard ratio for the composite outcome was 1.03 (95% CI 0.94, 1.14) among individuals with IBD who underwent appendectomy, relative to those who did not undergo appendectomy, after adjusting for sex, age, family history of IBD, degree of urbanization, time since IBD diagnosis, year of entry, and number of composite outcome events in the year before entry. In analysis of each outcome separately as well as for IBD subtypes Crohn’s disease (CD) and UC, results were consistent (Figure). There was no difference in the risk of colorectal cancer between the two groups (aHR 1.00, 95% CI 0.50–1.99). Conclusion Appendectomy following diagnosis is not associated with any beneficial or detrimental outcomes both in UC and CD. Conflict of interest: Dr. Agrawal, Manasi: This study is supported by the European Crohn’s and Colitis Foundation Grant - Ascertaining the role of the appendix in inflammatory bowel disease in a population-based cohort Vinkel Hansen, Anne: Anne Vinkel Hansen discloses no conflicts of interest Colombel, Jean-Frédéric: Grant: AbbVie, Janssen Pharmaceuticals, Takeda, Prometheus and Bristol Myers Squibb Lectures from: AbbVie, Roche and Takeda Other: AbbVie, Amgen, AnaptysBio, Allergan, Apini, Arena Pharmaceuticals, Astellas, Boehringer Ingelheim, Bristol Myers Squibb, candidrx Celgene, Celltrion, Clearview Curogen, Eli Lilly, Envision Pharma Ferring Pharmaceuticals, Galmed Research, Glaxo Smith Kline, Roche, Janssen Pharmaceuticals, Kaleido Biosciences, Immunic, Iterative Scopes, Landos, Microba Life Science, Merck, Mirador, Novartis, Otsuka Pharmaceutical, Owkin, Pfizer, Protagonist Therapeutics, Sanofi, Sun Pharma, Takeda, Teva, TiGenix, and is holding stock options in Intestinal Biotech Development Jess, Tine: Personal Fees: Consultancy for Ferring, Pfizer, Johnson & Johnson
Agrawal et al. (Thu,) studied this question.