[1] Vardcentralen Varmlands Nysater, Primary Care Res Unit, Nysater, Varmland County, Sweden
[2] Univ Orebro, Sch Hlth & Med Sci, SE-70182 Orebro, Sweden
[3] Univ Oslo, Inst Hlth & Soc, Dept Hlth Management & Hlth Econ, Oslo, Norway
[4] Uppsala Univ, Dept Med Sci, Uppsala, Sweden
[5] Uppsala Univ, Uppsala Clin Res Ctr, Uppsala, Sweden
[6] Karolinska Inst, Natl Board Hlth & Welf, Stockholm, Sweden
[7] Karolinska Inst, Dept Med Epidemiol & Biostat, S-17177 Stockholm, Sweden
[8] Reg Canc Ctr, Uppsala, Sweden
[9] Orebro Univ Hosp, Dept Paediat, Orebro, Sweden