[1] Univ Cologne, Univ Klinikum Koln AoR, Med Fak, Klin & Poliklin Kinder & Jugendmed, Kerpener Str 62, D-50937 Cologne, Germany
[2] Univ Cologne, Uniklin Koln, Kerpener Str 62, D-50937 Cologne, Germany
[3] Univ Cologne, Univ Klinikum Koln AoR, Med Fak, Klin & Poliklin Allgemein Viszeral & Tumorchirurg, Cologne, Germany