Appendectomy and the clinical course of ulcerative colitis: a retrospective cohort study and a nested case-control study from Korea.

Background and Aim Appendectomy protects against the development of ulcerative colitis (UC). However, the relationship between appendectomy and the clinical course of UC is complex, and could be impacted by a number of variables. The aim of this study was to compare the clinical course of UC between appendectomized patients and nonappendectomized patients in Korea. Methods Data on 2648 UC patients were retrieved from the Inflammatory Bowel Disease registry at Asan Medical Center. This retrospective cohort study compared the clinical course of UC in 68 patients who received an appendectomy before their UC diagnosis and 2544 patients who did not receive this procedure. A nested case–control study was also conducted to compare the disease course before and after appendectomy in 36 patients who received this surgery after UC diagnosis. To control for potential confounders, 144 matched controls were retrieved from among 2544 nonappendectomized patients Results In the retrospective cohort study, an appendectomy before UC diagnosis demonstrated no influence on disease extent at diagnosis, rates of medication use, proximal disease extension, or colectomy. The 10- and 20-year probabilities of receiving a colectomy were 12.7% and 20.6%, respectively, in appendectomized patients, in comparison with 8.9% and 16.4%, respectively, in nonappendectomized patients (P = 0.81). According to the nested case–control study, an appendectomy after UC diagnosis did not change the subsequent disease course in terms of medication use, proximal disease extension, or hospital admission rate. The adjusted ratio of hospital admissions after appendectomy versus before appendectomy was 1.01 (95% confidence interval = 0.46–2.23; P = 0.97). Conclusions Appendectomies performed before or after UC diagnosis do not affect its clinical course in the Korean population.