[1] Natl Inst Hlth & Welf, Dept Publ Hlth Solut, Helsinki, Finland
[2] Univ Oulu, Inst Hlth Sci, Oulu, Finland
[3] Oulu Univ Hosp, Med Res Ctr Oulu MRC Oulu, Res Unit Pediat Dermatol Clin Genet Obstet & Gyne, PEDEGO Res Unit, Oulu, Finland
[4] Univ Oulu, Oulu, Finland
[5] Univ Helsinki, Dept Psychol & Logoped, Helsinki, Finland
[6] Univ Helsinki, Dept Gen Practice & Primary Hlth Care, Helsinki, Finland
[7] Helsinki Univ Hosp, Helsinki, Finland
[8] Folkhalsan Res Ctr, Helsinki, Finland
[9] Univ Warwick, Dept Psychol, Warwick, England
[10] Univ Helsinki, Childrens Hosp, Helsinki, Finland
[11] Univ Helsinki, Cent Hosp, Helsinki, Finland
[12] Imperial Coll, London, England