Disease behavior in children with Crohn's disease: the effect of disease duration, ethnicity, genotype, and phenotype.

Background: Disease behavior in Crohn's disease (CD) may be modified by disease location and genotype. Disease behavior may change over time, and thus analysis requires follow-up. To date, there have been few pediatric studies that have evaluated the association between disease behavior and genotype with prolonged follow-up. The aim of our study was to evaluate the effect of genotype, phenotype, and ethnicity on disease behavior in pediatric CD.
Methods: Evaluation of 128 pediatric CD was followed by analysis of 232 pediatric and adult-onset CD patients. Inclusion required at least 2 years of follow-up. Phenotype, ethnicity, and disease duration were recorded. Patients were genotyped for polymorphisms in the NOD2/CARD15 gene.
Results: Colonic involvement was more frequent in younger patients. Pediatric disease at end of follow-up was classified as inflammatory (78%), penetrating (7%), and stricturing (17%). Duration of follow-up (mean 4.9 pediatric and 6.4 years mixed) was associated with more stricturing and penetrating disease. There was no association between mean age of onset and NOD2/CARD15, or either of these with disease behavior. These observations were replicated in the mixed cohort. Sephardic Jewish origin was inversely correlated with inflammatory behavior (P = 0.006), independent of NOD2/CARD15 genotype.
Conclusions: Duration of disease and ethnicity, irrespective of NOD2/CARD15 genotype and age of onset, were the only predictors for penetrating or stricturing disease.