1. School of Medical Sciences, Örebro University, SE 701 82 Örebro, Sweden
2. Clinical Epidemiology and Biostatistics, School of Medical Sciences, Örebro University, Örebro, Sweden
3. Department of Clinical Chemistry, Laboratory Medicine, University Hospital, Lund, Sweden
4. Clinical Epidemiology Unit, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
5. Department of Epidemiology and Public Health, University College, London, UK