- This study used a pathology database to compare 10,552 patients with microscopic colitis and 52,624 propensity-matched population comparators
- The subgroup with collagenous colitis was at significantly increased risk of hospital admission for COVID-19 (HR, 3.40) and significantly increased risk of severe COVID-19 (HR=2.48) compared with the controls
- The subgroup with lymphocytic colitis was not at significantly increased risk of either of those primary outcomes
- A single-nucleotide polymorphism at a previously established COVID-19 genetic risk locus was significantly more common in patients with collagenous colitis than those with lymphocytic colitis (allele frequencies 0.097 vs. 0.047; P=.005)
- It appears that pathogenetic mechanisms, still to be determined, might be shared between collagenous colitis and COVID-19 incidence and/or severity
Microscopic colitis has been linked to increased risk of death from infectious causes, as Massachusetts General Hospital researchers previously reported in Clinical Gastroenterology and Hepatology.
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Now, in the first study of its kind published in Gastroenterology, Hamed Khalili, MD, MPH, gastroenterologist and internist in the Mass General Clinical and Translational Epidemiology Unit and Division of Gastroenterology, and colleagues have linked collagenous colitis (CC), a subtype of microscopic colitis, to increased risk of severe COVID-19. Additionally, a variant at a gene locus already linked to increased risk of severe COVID-19 was more common in patients with CC than those with lymphocytic colitis (LC), another subtype of microscopic colitis.
Methods: Matched Cohort Study
The research was conducted with the use of the Epidemiology Strengthened by histoPathology Reports in Sweden (ESPRESSO) study, which gathered biopsy data from all 28 of Sweden's pathology departments. Among the patients still alive as of February 1, 2020, they matched 10,552 who had microscopic colitis diagnosed between January 1, 1990, and December 31, 2016, with 52,624 comparators according to propensity scores that reflected demographics, comorbidities and medications.
The patients were followed from February 1, 2020, until death, development of severe COVID-19, or July 31, 2020, whichever came first. Severe COVID-19 was defined as the composite of ICU admission for COVID-19, death from COVID-19 or death from any cause within 30 days of hospital admission for COVID-19.
Analysis showed that in the overall cohort with microscopic colitis, there was an increased risk of COVID-19 (HR, 1.27) vs. population comparators, no increased risk of hospitalization for COVID-19 and no increased risk of severe COVID-19.
In the CC subgroup, there was an increased risk of COVID-19 (HR, 1.72), a significantly increased risk of hospitalization for COVID-19 (HR, 3.40) and a significantly increased risk of severe COVID-19 (HR, 2.48).
The LC subgroup did not show any increased risk of any of the three aforementioned outcomes.
Pilot Genetic Study
The researchers also examined genotyping data on 359 patients with CC and 172 with LC, previously recruited at tertiary gastroenterology clinics in Sweden. The single-nucleotide polymorphism rs13071258 at gene locus 3p21.31 was significantly more common in patients with CC than those with LC (allele frequencies 0.097 vs. 0.047; P=0.005).
Interpreting the Findings
The association between CC and the risk of poor COVID-19 outcomes may be related at least in part to genetic factors that modify the immune response to viral pathogens. The 3p21.31 cluster appears to be associated with COVID-19 respiratory failure (published in The New England Journal of Medicine). It is also known to harbor six genes that have functions relevant to microscopic colitis.
If these findings are corroborated, they will suggest that pathogenetic mechanisms, still to be determined, are shared between CC and COVID-19 incidence and/or severity.
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