Background: Ulcerative colitis (UC) is a chronic inflammatory disease usually responding well to anti-inflammatory drugs but many patients will eventually need a colectomy, due to severe acute colitis or chronically active disease. Appendectomy has previously been shown to be associated with a lower risk of developing UC later in life. We aimed to assess the association between appendectomy and disease activity and the risk of having a colectomy in UC patients.
Methods: All patients in Sweden with a UC diagnosis between 1964 and 2010 were identified from the National Patient Register. Information regarding appendectomy with or without appendicitis was gathered, including appendectomy both prior to and after the UC diagnosis. Planned and unplanned hospital admissions for UC as well as colectomy were used as markers of disease activity.
Results: Appendectomy was performed in 2,143 of the 63,711 UC patients, prior to the UC diagnosis in 1,537 patients and after in 606 patients.
In all, 7,690 patients underwent colectomy. The cumulative risk of colectomy for patients without appendectomy was 0.10 (95% CI 0.09 to 0.10) and 0.13 (0.12 to 0.13) after 5 and 10 years, respectively. For patients with appendectomy for appendicitis before the age of 20 and prior to UC diagnosis, the cumulative risk of colectomy was 0.05 (0.03 to 0.09) and 0.07 (0.04 to 0.11), respectively. In multivariable analysis the hazard ratio for this group was 0.44 (0.27 to 0.72) compared to UC patients without appendectomy. Appendectomy prior to UC diagnosis but at age 20 years or older did not affect the risk of colectomy after UC diagnosis (HR 0.97 (0.80 to 1.18)). Appendectomy for appendicitis after the UC diagnosis was associated with an increased risk of colectomy with HR 1.55 (1.20 to 2.02). Appendectomy after UC diagnosis for other reasons did not affect the risk of colectomy (HR 1.14 (0.57 to 2.28)).
Appendectomy prior to UC diagnosis was associated with fewer planned and unplanned admissions for UC (Incidence rate ratio 0.71 (0.64 to 0.77), whereas appendectomy after UC diagnosis was associated with more admissions for UC (IRR 1.10 (1.00 to 1.21)).
Conclusions: UC patients with a history of appendicitis before the age of 20 years and preceding the UC diagnosis have a lower risk for colectomy. Appendectomy for appendicitis after the UC diagnosis is associated with more admissions and increased risk of colectomy. Appendectomy for other reasons after the UC diagnosis does not seem to affect the severity of UC. Appendectomy therefore does not appear to be a treatment option in UC.