Appendectomy carries modest risk of microscopic colitis

Undergoing appendectomy may put patients at risk of developing subsequent microscopic colitis, although the risk increase appears to be modest, as shown in a study.

The analysis used data from the nationwide case-control study ESPRESSO cohort that involved histopathological examinations in Sweden, linked to national registers. A total of 14,520 patients with microscopic colitis were matched to 69,491 population controls according to age, sex, calendar year of biopsy, and county of residence.

Researchers obtained data on antecedent appendectomy and comorbidities from the patient register. They used unconditional logistic regression models to assess the potential association between appendectomy and microscopic colitis, with further analysis performed based on colitis subtypes (lymphocytic colitis and collagenous colitis), follow-up time post-appendectomy, and severity of appendicitis.

A total of 1,103 (7.6 percent) patients with microscopic colitis and 3,510 (5.1 percent) controls had a previous appendectomy ≥1 year prior to index event/matching date. A previous appendectomy was associated with a 50-percent increased risk of microscopic colitis overall (odds ratio [OR], 1.50, 95 percent confidence interval [CI], 1.40–1.61). This was true for both collagenous (OR, 1.67, 95 percent CI, 1.48–1.88) and lymphocytic (OR, 1.42, 95 percent CI, 1.30–1.55) subtypes.

The risk remained elevated throughout follow-up, and the highest risk was observed in noncomplicated appendicitis.

The findings highlight the potential of appendectomy to have immunomodulating effects in the colon, influencing the development of microscopic colitis.