P320 Factors determining therapeutic strategy at diagnosis and evolution of disease severity in a cohort of Belgian pediatric Crohn's disease patients (BELCRO)

Abstract

Background: The effect of biological therapy on surgical rates in Crohn’s disease (CD) is unclear. Our objective is to describe the post-biologic surgical incidence and identify prognostic factors. Methods: A CD cohort (n = 104) prescribed infliximab or adalimumab between 1/7/2000 and 29/6/2011 was identified. The primary outcome was post-biologic CD-related surgery. The primary exposure of interest was disease behavior at onset of first biologic: inflammatory (B1), fibrostenotic (B2) or penetrating disease (B3). Secondary factors collected were: age at diagnosis; sex; time from diagnosis to onset of first biologic; and pre-biologic surgical history. The surgical rate following the start of the first biologic was calculated assuming a Poisson distribution. Kaplan Meier (KM) survival curves of post-biologic surgery, stratified by disease behavior at onset of biologics, were compared using the log rank test. Cox proportional regression model evaluated the effect of prebiologic disease behavior (B1 referent versus B2 and B3) on the post-biologic surgical risk after adjusting for confounders. Risk estimates were presented as hazard rate ratios (HR) with 95% confidence intervals (CI). Results: 26.0% of CD patients underwent post-biologic surgery (0.09 per person-year; 95% CI 0.06 0.13). B2 (mean time to surgery = 1.6±0.17 years; figure 1) and B3 (mean time to surgery = 1.4±0.08 years) disease behavior showed a significant (p = 0.002) increase in surgical rates when compared to B1 (mean time to surgery = 7.3±0.48 years). B2 (HR = 10.7; 95% CI: 3.3 37.5; p = 0.0001) and B3 (HR = 4.2; 95% CI: 1.2 15.4; p = 0.027) disease behavior at onset of the first biologic showed a significantly increased risk for surgery as compared to B1 after adjusting for age at the onset of biologic (HR = 1.0; 95% CI: 0.97 1.03), pre-biologic surgical status (HR = 0.48; 95% CI: 0.18 1.3), time from diagnosis to onset of biologic (HR = 0.97; 95% CI: 0.91 1.03), and pre-biologic perianal disease (HR = 1.9; 95% CI: 0.75 5.1). Conclusions: Complicated CD behavior at the start of biological therapy is a significant predictor of surgery. Treating CD at the inflammatory stage may improve disease outcomes.