[1] Karolinska Inst, Dept Med Epidemiol & Biostat, Nobels Vag 12A,Box 281, S-17177 Stockholm, Sweden
[2] Karolinska Inst, Karolinska Univ Sjukhuset Huddinge, Div Pathol, Dept Lab Med, H5, S-14186 Stockholm, Sweden
[3] Univ Iceland, Ctr Publ Hlth Sci, Fac Med, IS-101 Reykjavik, Iceland
[4] Harvard Sch Publ Hlth, Dept Epidemiol, 677 Huntington Ave, Boston, MA 02115 USA
[5] Univ Orebro, Sch Med Sci, Clin Epidemiol & Biostat, Orebro, Sweden