1. Technische Universität München Klinikum rechts der Isar; Institut für Allgemeinmedizin / Institute of General Practice; Orleansstrasse 47 Munich Germany 81667
2. Huisartsen Oog in Al; Handelstraat 55a Utrecht Utrecht Netherlands 3533GH
3. Tufts Medical Centre/Division of Gastroenterology; Tufts Medical Centre; 800 Washington Street Box 63 Boston MA USA 02111
4. Brown University Public Health Program; Center for Evidence-based Medicine; 121 S. Main Street Providence RI USA 02912
5. VU University Medical Center; Department of General Practice and Elderly Care Medicine, EMGO Institute for Health and Care Research, and Alzheimer Center; Van der Boechorststraat 7 12 Amsterdam Netherlands