The impact of co-existing immune-mediated diseases on phenotype and outcomes in inflammatory bowel diseases.

BACKGROUND: Inflammatory bowel diseases lead to progressive bowel damage and need for surgery. While the increase in prevalence of other immune-mediated diseases in IBD is well recognised, the impact of this on the natural history of IBD is unknown.

AIM: To determine the impact of concomitant immune-mediated diseases on phenotypes and outcomes in IBD.

METHODS: Patients with IBD enrolled in a prospective registry were queried about the presence of other immune-mediated diseases, defined as those where immune dysregulation plays a role in pathogenesis. Demographics and disease-related information were obtained. Subjects also completed measures of quality of life. Multivariable regression models compared disease phenotype and outcomes of IBD patients with and without other immune-mediated diseases.

RESULTS: The cohort included 2145 IBD patients among whom 458 (21%) had another immune-mediated disease. There was no difference in CD phenotype between the two groups. UC patients were more likely to have pancolitis in the presence of another immune-mediated disease (62%) compared to those without (52%, P = 0.02). IBD patients with another immune-mediated disease had higher rates of needing anti-TNF biologics [Odds ratio (OR) 1.31, 95% CI 1.05-1.63] and surgery (OR 1.26, 95% CI 0.99-1.61). The presence of another immune-mediated disease was also associated with lower disease-specific and general physical quality of life.

CONCLUSIONS: The presence of another immune-mediated disease in IBD patients was associated with higher likelihood of pancolonic involvement in UC, and a modest increase in need for IBD-related surgery and anti-TNF biological therapy. Such patients also experienced worse quality of life.