[1] Natl Inst Hlth & Welf, Dept Chron Dis Prevent, Helsinki, Finland
[2] Univ Helsinki, Dept Gen Practice & Primary Hlth Care, FIN-00014 Helsinki, Finland
[3] Vasa Cent Hosp, Dept Med, Vaasa 65130, Finland
[4] Folkhalsan Res Ctr, Helsinki, Finland
[5] Univ Helsinki, Cent Hosp, Unit Gen Practice, FIN-00014 Helsinki, Finland
[6] Univ Helsinki, Cent Hosp, Hosp Children & Adolescents, FIN-00014 Helsinki, Finland
[7] Univ Helsinki, FIN-00014 Helsinki, Finland
[8] Univ Southampton, Southampton Gen Hosp, MRC Lifecourse Epidemiol Unit, Southampton, Hants, England