The association between microscopic colitis and celiac disease: a systematic review and meta-analysis.

Background: Multiple studies suggested that celiac disease (CD) may be associated with microscopic colitis (MC); however, most were limited by a small sample size or the main scope of interest. We aimed to analyze previously published literature on this association to determine its extent and significance. Methods: A systematic review was conducted in PubMed, Embase, PubMed Central, Cochrane, and ScienceDirect databases from inception through January 2022. The PRISMA guideline was followed for data extraction. Effect estimates were extracted and combined using random effect, the generic inverse variance method of DerSimonian and Laird and pooled odds ratio (OR), and event rates (ER) were calculated. The Newcastle-Ottawa scale was used to evaluate the risk of bias. Forest plots were generated and publication bias assessed via conventional techniques. Results: Twenty-six studies with a total of 22,802 patients with MC were included in this analysis. CD was significantly associated with MC (odds ratio [OR] 8.276, 95% confidence interval [CI] 5.888-11.632; P<0.001). The ER for MC in CD patients was 6.2% (95%CI 4.1-9.2%; P<0.001), while the ER for CD in MC patients was 6.1% (95%CI 3.9-9.5%; P<0.001). CD was prevalent in both types of MC: 5.2% (95%CI 2.2-12.1%; P<0.001) in collagenous colitis and 6.3% (95%CI 3.4-11.5%; P<0.001) in lymphocytic colitis. We found no publication bias, according to funnel plots and Egger's regression asymmetry testing. Conclusions: Our meta-analysis confirms a statistically significant association between CD and MC, with a high prevalence of CD in both types of MC. Gastroenterologists should be wary of this association when evaluating patients with either disease, particularly patients with a suboptimal response to first-line therapy.