1. Department of Pediatrics, Medical University Munich, Munich, Germany
2. Department of Pediatrics, Medical University of Berlin, Berlin, Germany
3. Department of Pediatrics, University Hospital Jena, Jena, Germany
4. Department of Pediatrics, Medical University of Göttingen, Göttingen, Germany
5. Department of Pediatrics, Evangelisches Krankenhaus Bielefeld, Bielefeld, Germany
6. Department of Pediatrics, Medical University of Graz, Graz, Austria
7. Institute of Epidemiology and Medical Biometry, University of Ulm, Ulm, Germany