1. Departments of Internal Medicine, Gastroenterology, and Hepatology, Medisch Centrum Haaglanden, P.O. Box 432, 2501 CK The Hague, The Netherlands
2. Department of Gastroenterology and Hepatology, Isala Clinics, P.O. Box 10500, 8000 GM Zwolle, The Netherlands
3. Department of Gastroenterology and Hepatology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands