1. Unit of Pharmacotherapy Epidemiology and Economics Department of Pharmacy University of Groningen Groningen The Netherlands
2. Department of Clinical Pharmacy and Pharmacology Medical Centre Leeuwarden Leeuwarden The Netherlands
3. Department of Internal Medicine Medical Centre Leeuwarden Leeuwarden The Netherlands
4. Science Bureau Medical Centre Leeuwarden Leeuwarden The Netherlands
5. Department of Epidemiology University of Groningen University Medical Centre Groningen Groningen The Netherlands
6. Pathology Friesland Leeuwarden The Netherlands
7. Department of Haematology Amsterdam University Medical Centre Amsterdam The Netherlands