1. Department of Pediatrics and Adolescence Medicine, Freiburg University Hospital, Freiburg, Germany
2. Olgahospital, Children’s Hospital, Stuttgart, Germany
3. Department of Pediatrics, Heidelberg University Hospital, Heidelberg, Germany
4. Department of Pediatrics, Magdeburg University Hospital, Magdeburg, Germany
5. Otto-Heubner Center of Pediatrics and Adolescents Medicine, Charité, Humboldt University Hospital, Berlin Germany
6. Clinic for Pediatrics, Protestant Hospital, Oberhausen, Germany
7. Department of Epidemiology, Ulm University, Ulm, Germany