1. Department of Clinical Epidemiology Leiden University Medical Center Leiden The Netherlands
2. Fred Hutchinson Cancer Research Center Seattle WA USA
3. Department of Medicine Larner College of Medicine University of Vermont Burlington VT USA
4. Department of Haematology Akershus University Hospital Lørenskog Norway
5. Institute of Clinical Medicine University of Oslo Oslo Norway
6. Department of Haematology Oslo University Hospital Oslo Norway
7. National Heart, Lung, and Blood Institute Bethesda MD USA