Sweden: A recent study led by John Maret-Ouda and colleagues found a modestly higher chance of developing microscopic colitis (MC) after appendectomy. The findings of this study were published in Clinical Gastroenterology and Hepatology.

Microscopic colitis is a kind of inflammatory bowel disease that causes persistent diarrhea. Appendectomy may have immunomodulatory effects on the colon, lowering the risk of gastrointestinal illness. The link between appendectomy and MC has received little attention. As a result, this study was carried out to investigate the link between microscopic colitis and appendectomy.

In genetically predisposed individuals, the pathophysiology of microscopic colitis is thought to be associated with a dysregulated immune response in the gut mucosa, and infiltration of T-helper cells 17 (Th17) in the lamina propria of colon has indeed been observed, contributing that appendicitis has been related to upregulation of the Th17 pathway.

The study was a case-control study based on the countrywide ESPRESSO cohort, which included histopathological exams across Sweden that were connected to national registers. Individuals with MC were paired to population controls based on gender, age, biopsy year, and county of residence. The Patient Register was queried for information on previous appendectomy and comorbidities. Unconditional logistic regression models with odds ratios (ORs) and 95% confidence intervals (Cl) modified for country of birth and matching covariates were run. Sub-analyses were performed depending on MC subtypes (collagenous colitis [CC] and lymphocytic colitis [LC]), post-appendectomy follow-up time, and severity of appendicitis.

The key findings of this study were as follows:

1. The study comprised 14,520 instances of MC and 69,491 controls, with 7.6% (n=1,103) and 5.1% (n=3,510) having had an appendectomy 1 year prior to the MC/matching date, respectively.

2. Patients who had previously undergone an appendectomy had an elevated incidence of MC overall, as well as per subtype CC, LC.

3. The risk remained higher throughout the study, with non-complicated appendicitis having the highest risk.


Maret-Ouda, J., Ström, J. C., Roelstraete, B., Emilsson, L., Joshi, A. D., Khalili, H., & Ludvigsson, J. F. (2022). Appendectomy and future risk of microscopic colitis: a population-based case-control study in Sweden. In Clinical Gastroenterology and Hepatology. Elsevier BV. https://doi.org/10.1016/j.cgh.2022.05.037

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