[1] Kanta Hame Cent Hosp, Dept Pediat Surg, Hameenlinna 13530, Finland
[2] Helsinki Univ Hosp, Childrens Hosp, Dept Pediat Surg, Helsinki, Finland
[3] Helsinki Univ Hosp, Dept Plast Surg, Helsinki, Finland
[4] Helsinki & Uusimaa Hosp Dist, Adm Res & Dev, Helsinki, Finland
[5] Univ Eastern Finland, Res Ctr Comparat Effectiveness & Patient Safety, Dept Hlth & Social Management, Kuopio, Finland
[6] Univ Helsinki, Dept Publ Hlth, Hjelt Inst, Helsinki, Finland