1. Department of Internal Medicine, University of Oulu, Kajaanintie 50, FIN-90220 Oulu, Finland and Biocenter Oulu, University of Oulu, Kajaanintie 52, FIN-90220 Oulu, Finland
2. National Public Health Institute (KTL), Mannerheimintie 166, FIN-00300, Helsinki, Finland