Clinical course in Crohn's disease: factors associated with behaviour change and surgery.

A behaviour progression was observed in about one-sixth of the patients. Progression to a stricturing pattern was the most frequent change in behaviour. Stricturing and penetrating behaviour, higher number of hospitalisations in the first year of diagnosis, use of steroids at diagnosis, smoking status, age at diagnosis <16 years and ileocolic disease location were associated with an unfavourable clinical evolution.