Introduction: Immunosuppression, the cornerstone of management of Crohn's disease (CD) and ulcerative colitis (UC) (inflammatory bowel diseases; IBD) is associated with an increased risk of serious infections that is inadequately predicted by clinical risk factors. The role of genetics in determining susceptibility to infections is unknown.
Methods: From a prospective-consented patient registry, we identified IBD patients with serious infections requiring hospitalization. Analysis was performed to identify IBD-related and non-IBD related immune response loci on the Immunochip that were associated with serious infections and a genetic risk score (GRS) representing the cumulative burden of the identified single nucleotide polymorphisms was calculated. Multivariable logistic regression used to identify effect of clinical and genetic factors.
Results: The study included 1333 IBD patients (795 CD, 538 UC) with median disease duration of 13 years. A total of 133 patients (10%) had a serious infection requiring hospitalization. Patients with infections were more likely to have CD and had shorter disease duration. The most common infections were skin and soft-tissue, respiratory and urinary tract infections. Eight IBD risk loci and two other polymorphisms were significantly associations with serious infections. Each one point increase in the infection GRS was associated with a 50% increase in risk of infections (OR = 1.53, 95% CI = 1.37-1.70) (p = 1 × 10-14), confirmed on multivariable analysis. Genetic risk factors improved performance of a model predicting infections over clinical covariates alone (p < 0.001).
Conclusions: Genetic risk factors may predict susceptibility to infections in patients with IBD.
Keywords: Crohn’s disease; Genetics; immunosuppression; infections; pneumonia; sepsis.