Appendectomy before or after ulcerative colitis diagnosis is not associated with improved long-term outcomes: a multicenter real-world study

BACKGROUND: Appendectomy has been proposed to influence ulcerative colitis (UC) outcomes, but its effect based on timing before or after diagnosis and long-term UC outcomes remains unclear. MATERIALS AND METHODS: Using TriNetX U.S. Collaborative Network, we identified adults with UC (2010-2024) who underwent appendectomy before or after diagnosis. Two 1:1 propensity score-matched comparisons were performed: appendectomy-before-UC and appendectomy-after-UC versus controls. The primary outcome was a 5-year composite of oral/intravenous (IV) corticosteroid use or colectomy. Secondary outcomes included individual composite outcomes and advanced therapy initiation in biologic-naive patients. Subgroup analyses stratified by age and biologic exposure were also performed. RESULTS: After matching, appendectomy after UC diagnosis showed no association with the composite outcome (aHR 0.98, 95% CI, 0.83-1.16), oral steroids (aHR 0.90, 95% CI, 0.75-1.09), IV steroids (aHR 1.11, 95% CI, 0.87-1.43), colectomy (aHR 1.24, 95% CI, 0.77-1.99), or advanced therapy initiation (aHR 0.97, 95% CI, 0.63-1.48). Appendectomy before UC diagnosis also showed no difference in the composite outcome (aHR 0.91, 95% CI, 0.76-1.09), oral steroids (aHR 0.88, 95% CI, 0.72-1.08), colectomy (aHR 0.99, 95% CI, 0.60-1.63), or advanced therapy initiation (aHR 0.77, 95% CI, 0.53-1.13). However, IV steroid use was reduced (aHR 0.68, 95% CI, 0.51-0.90, P = .006). In subgroup analyses, advanced therapy initiation was lower in patients aged 18-40 years following appendectomy after UC diagnosis (aHR 0.56, 95% CI, 0.33-0.96, P = .03). CONCLUSION: Appendectomy was not associated with improved long-term UC outcomes of oral/IV steroid use, colectomy or initiation of advanced therapy regardless of timing.