[1] Ryhov Cty Hosp, Dept Pediat, SE-55185 Jonkoping, Sweden
[2] Univ Gothenburg, Dept Pediat, Inst Clin Sci, Sahlgrenska Acad, Gothenburg, Sweden
[3] Nord Sch Publ Hlth, Gothenburg, Sweden
[4] Univ Gothenburg, Dept Psychol, S-40020 Gothenburg, Sweden