Appendectomy and the risk of microscopic colitis - A systematic review and meta-analysis.

Background: Microscopic colitis (MC), a chronic intestinal inflammatory disorder characterised by persistent watery diarrhoea, is categorised into collagenous and lymphocytic subtypes. Recent studies suggest that appendectomy influences the risk of MC, although the evidence remains inconclusive. This meta-analysis of available research was conducted to clarify the relationship between appendectomy and MC risk.

Methods: In accordance with the PRISMA guidelines, a comprehensive search was conducted in the Web of Science, EMBASE, and PubMed up to January 2024, focusing on studies that explored the association between appendectomy and MC. Quality was assessed using the Newcastle-Ottawa Scale, with data synthesis using the DerSimonian and Laird random-effects model. Heterogeneity and potential biases were evaluated; subgroup analyses were performed to investigate specific associations.

Results: Six studies were analysed, including one cohort and five case-control studies involving 85,845 participants. The combined analysis showed no significant link between appendectomy and MC risk (OR: 1.20, 95% CI: 0.91-1.58), despite moderate heterogeneity (I² = 59%). Subgroup analyses indicated potential associations in specific contexts. Notably, significant associations were found in subgroups based on MC subtypes (CC: OR 1.59, 95% CI: 1.20-2.10; LC: OR 1.45, 95% CI: 1.34-1.58), unadjusted ORs (OR 1.42, 95% CI: 1.17-1.73), healthy control groups (OR 1.51, 95% CI: 1.38-1.67) and studies using medical records for appendectomy history (OR 1.50, 95% CI: 1.28-1.75). Other subgroup analyses did not yield significant results.

Conclusion: This meta-analysis did not support a significant association between appendectomy and increased risk of MC. These findings highlight the need for further large-scale, prospective studies to explore this relationship in greater detail, considering the potential for nuanced interactions and the impacts of various confounding factors.