[1] Aalborg Univ Hosp, Dept Social Med, Havrevangen 1, DK-9000 Aalborg, Denmark
[2] Aalborg Univ, Dept Clin Med, Gistrup, Denmark
[3] Odense Univ Hosp, Ctr Clin Epidemiol, Odense, Denmark
[4] Univ Southern Denmark, Dept Clin Res, Res Unit Clin Epidemiol, Odense, Denmark
[5] Aalborg Univ, Dept Hlth Sci & Technol, Publ Hlth & Epidemiol, Gistrup, Denmark
[6] Aalborg Univ Hosp, Res Data & Stat, Aalborg, Denmark
[7] Odense Univ Hosp, Res Unit Surg, Odense, Denmark
[8] Univ Southern Denmark, Dept Clin Res, Odense, Denmark
[9] Karolinska Inst, Dept Clin Sci & Educ, Sodersjukhuset, Stockholm, Sweden
[10] Karolinska Inst, Dept Med, Clin Epidemiol Div, Solna, Stockholm, Sweden
[11] SachsChildren & Youth Hosp, Sodersjukhuset, Stockholm, Sweden
[12] Odense Univ Hosp, Hans Christian Andersen Childrens Hosp, Odense, Denmark