Crohn's disease phenotype, prognosis, and long-term complications: what to expect?

According to Montreal classification, different phenotypes of Crohn's disease are defined taking into account age at diagnosis, localization of digestive lesions at first surgery, and cumulative anatomical behaviour. This classification is supported by the increased severity of the disease when diagnosed in childhood, the relative stability of disease localization over time, and the clinical importance of intestinal complications as stricture and abscess or fistula formation. However, type and delay of complications are dependent on disease localization (they develop early in small bowel disease and late in colitis), every patient will develop complications one day, and perianal disease may be an important problem observed in up to half the patients. The percentage of patients with active disease every year remains stable, about 40%, after the 3 first years, and only a few patients have long periods of remission. Intestinal resections are required in the majority of patients during life, and many are operated on several times. Prognosis is hampered by iterative surgery, cancer and side-effects of treatment. Standardized mortality ratio is 1.50. Although occurrence of complications, need for surgery and mortality did not change significantly through the years 1950-2000, there are some signals suggesting that new therapetic strategies (immunosuppressants earlier in high risk patients) and biologics will modify natural history and improve the long-term prognosis.