[1] Stockholm South Gen Hosp, Sachs Children & Youth Hosp, Stockholm, Sweden
[2] Karolinska Inst, Dept Med, Clin Epidemiol Unit, SE-17176 Stockholm, Sweden
[3] Karolinska Inst, Dept Clin Sci & Educ, Sodersjukhuset, SE-17176 Stockholm, Sweden
[4] Karolinska Inst, Inst Environm Med, SE-17176 Stockholm, Sweden
[5] Univ Uppsala Hosp, Dept Womens & Childrens Hlth, Uppsala, Sweden
[6] Karolinska Inst, Dept Med Epidemiol & Biostat, SE-17176 Stockholm, Sweden
[7] Orebro Univ Hosp, Dept Pediat, Orebro, Sweden
[8] Karolinska Inst, Div Ear Nose & Throat Dis, Dept Clin Sci Intervent & Technol, SE-17176 Stockholm, Sweden
[9] Univ Gothenburg, Dept Internal Med, Inst Med, Sahlgrenska Acad, Gothenburg, Sweden
[10] Univ Gothenburg, Sahlgrenska Acad, Ctr Person Ctr Care, Gothenburg, Sweden