Evolution of clinical behaviour in Crohn's disease: predictive factors of penetrating complications

Background and aims. Crohn's disease is a heterogeneous entity. The Vienna Classification defines three different clinical patterns: non-stricturing. non-penetrating, 'stricturing' and 'penetrating'. Aim of this study was to assess the change in clinical behaviour over time and to evaluate whether all evolution towards penetrating complications can be predicted. Methods. A total of 139 patients with non-penetrating behaviour at the time of diagnosis were included. The mean follow-up was 4.84 years (range 1-23.2 years). The clinical behaviour, according to the Vienna Criteria, was assessed at the diagnosis and at the end of follow up. Statistical analysis was performed by means of the Kaplan-Meier method and standard logistic regression analysis. Results. The cumulative probability of a change in clinical behaviour was 22, 38 and 63% at 3, 6 and 12 years, respectively, and the cumulative probability of developing penetrating complications was 22, 33 and 55% at 3, 6 and 12 years, respectively. Young age at diagnosis (< 40 years) and a stricturing behaviour are independent risk factors of developing major penetrating complications (internal fistula, mass or abscess): OR = 6.0, 95% CI 1.1-30.5; OR = 4.0, 95% CI 1.5-10.9, respectively, but not perianal disease. Conclusions. The behavioural classification of Crohn's disease is a dynamic model in which each status should be considered as not fixed but evolutive. Perianal disease should be considered a distinct pattern of penetrating behaviour. (c) 2004 Editrice Gastroenterologica Italiana S.H. Published by Elsevier Ltd. All rights reserved.