1. Icelandic Heart Association Research Institute, Kopavogur, Iceland
2. Department of Clinical Biochemistry, Landspitali University Hospital, Reykjavik, Iceland
3. Faculty of Medicine, University of Iceland, Reykjavik, Iceland
4. Laboratory of Epidemiology, Demography and Biometry, Intramural Research Program, National Institute on Aging Bethesda, MD
5. Department of Medical Sciences, Uppsala University, Uppsala, Sweden