1. Department of Transfusion Medicine; Sanquin Blood Supply; Amsterdam, the Netherlands
2. Department of Internal Medicine, Division of Gastroenterology; Maastricht University Medical Centre; Maastricht, the Netherlands
3. Department of Methodology and Statistic; School for Public Health and Primary Care (CAPHRI), Maastricht University
4. Department of Clinical Epidemiology and Medical Technology Assessment
5. Department of Research; Sanquin Blood Supply
6. Department of Internal Medicine; Radboud University Nijmegen Medical Centre; Nijmegen, the Netherlands
7. Department of Internal Medicine; Zuyderland Medical Center; Heerlen/Brunssum/Sittard the Netherlands
8. Department of Internal Medicine, Division of Rheumatology