Association Between Serological Markers and Crohn's Disease Activity.

Background: The aim was to study the association between six serological markers and Crohn's disease (CD) activity at an inflammatory bowel disease (IBD) referral center.

Methods: We designed a retrospective cohort study using adults (> 18 years) with CD followed for at least 1 year at University of Alabama at Birmingham. Baseline serological markers ASCA-IgA, ASCA-IgG, anti-OmpC IgA, anti-CBir1 IgG, anti-A4Fla2 IgG and anti-FlaX IgG were drawn at initial visit. Poisson regression was used to assess the longitudinal relationship between these markers drawn at baseline and rate of active clinical disease during follow-up.

Results: Each marker, from 135 patients, was categorized into high vs. low. A Poisson regression model adjusted for age, gender, race, duration of disease, obesity, proton pump inhibitor; steroid and thiopurine use, and disease location demonstrated that CD patients with high anti-CBir1 IgG at baseline were approximately twice more likely to have active clinical disease (incidence rate ratio (IRR) 2.06, 95% confidence interval (CI) 1.28 - 3.33, P = 0.0032). The unadjusted Poisson regression model for A4Fla2 IgG antibody level did suggest that a high A4Fla2 IgG at baseline was associated with a higher likelihood of active CD (IRR 1.64, 95% CI 1.07, 2.53, P = 0.0238) which however, upon adjustment based on effect size, was not significant. The other four antibodies did not appear to predict clinical course.

Conclusions: High levels of anti-CBir1 IgG appear to be associated with a greater likelihood of active CD. Whether routine baseline testing for anti-CBir1 IgG to predict a more active clinical course is warranted needs more research.