Microscopic Colitis Is Associated With A Significantly Increased Risk Of Inflammatory Bowel Disease In The Us Population: A National Cohort Study

INTRODUCTION: Although the pathogenesis of microscopic colitis is unclear, the disease appears to have shared pathophysiology with inflammatory bowel disease (IBD). A recent population-based study from Sweden found a significant increase in the risk of incident IBD among patients with microscopic colitis. To date, there is no similar large population study from North America. We aimed to investigate the association of microscopic colitis and IBD in a US-based national database. METHODS: In this retrospective cohort study, the 2016-2017 National Inpatient Sample database was analyzed by using ICD-10 Code for hospitalizations with a primary or secondary diagnosis as microscopic colitis (MC), Crohn’s disease (CD), and ulcerative colitis (UC). Patients were divided into the MC group and the non-MC group. The outcome of interest was the prevalence of CD and UC in both MC and non-MC group. Multivariate regression was used to adjust for age and gender to investigate the impact of MC on the rate of CD and UC. STATA 14 (College Station, TX) was used for analysis. RESULTS: We identified 12,805 patients with MC hospitalized from 2016 to 2017, which was about 0.018% of all hospitalizations. The mean age was 70.9 and the percentage of females was 78.2%. There were 190 cases of CD (190/12,805, 1.48%, 95% CI: 1.08%–2.03%) in the MC group compared to 411,225 cases of CD (411,225/71,461,430, 0.58%, 95% CI: 0.57%–0.59%) in the non-MC group. MC was found to be associated with a significantly higher rate of CD with an adjusted odds ratio of 2.50 (95% CI: 1.82–3.43, P < 0.001).There were 250 cases of UC (250/12,805, 1.95%, 95% CI: 1.48%–2.57%) in the MC group compared to 245,585 cases of UC (245,585/71,461,430, 0.34%, 95% CI: 0.34%–0.35%) in the non-MC group. MC was found to be associated with a significantly higher rate of UC with an adjusted odds ratio of 5.11 [95% CI: 3.85–6.79, P < 0.001]. CONCLUSION: In this large population study based on the US, microscopic colitis was found to be associated with a significantly increased risk of IBD. Clinicians should be attentive to this association, as it aids in appropriate timely evaluations particularly in atypical gastrointestinal symptoms. Further studies are needed to investigate the underlying mechanism of this association.Table 1.: Microscopic Colitis risk of Crohn’s disease and Ulcerative colitis