1. Digestive Functional Disorders Unit, Hospital Universitario La Fe, Valencia, Spain
2. Center for Family and Community Medicine, Karolinska Instutitet, Stockholm, Sweden
3. Società Italiana Medicina Generale, Brescia, Italy
4. Wilhelminenspital, Vienna, Austria
5. Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
6. Medical Department, AstraZeneca, Madrid, Spain
7. Haukeland University Hospital, Bergen, Norway