1. Andres PG, Friedman LS. Epidemiology and the natural course of inflammatory bowel disease. Gastroenterol Clin N Am 1999; 28: 255–75.
2. Hanauer SB, Meyers S. Management of Crohn’s disease in adults. Am J Gastroenterol 1997; 92: 559–66.
3. Binder V. Prognosis and quality of life in patients with ulcerative colitis and Crohn’s disease. Int Disabil Stud 1988; 10: 172–4.
4. Torrance GW. Preferences for health outcomes and cost-utility analysis. Am J Manag Care 1997; 3: S8 - S20.
5. Spilker B. Quality of life and pharmacoeconomics in clinical trials, 2nd edn. Philadelphia: Lippencott-Raven, 1996.