1. Department of Dermatology University Hospital of Muenster Muenster Germany
2. Department of Dermatology University Hospital Tuebingen Tuebingen Germany
3. Department of Dermatology University Hospital Luebeck Luebeck Germany
4. Department of Dermatology, Venereology and Allergology HELIOS St. Elisabeth Hospital Oberhausen University Witten/Herdecke Oberhausen Germany
5. Department of Dermatology University Medical Center Hamburg‐ Eppendorf Hamburg Germany
6. Institute of Biostatistics and Clinical Research University of Muenster Muenster Germany