1. Centre for Paediatric and Adolescent Rheumatology, Schöen Klinik Eilbek, Hamburg, Germany
2. German Rheumatism Research Centre Berlin, A Leibniz Institute, Berlin, Germany
3. Institute for Social Medicine, Epidemiology and Health Economics, Charité University Medicine, Berlin, Germany
4. Department of Medical Biometry and Epidemiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
5. Department of Orthodontics, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany