1. Clinic of Vascular Medicine, HELIOS Klinik Krefeld, Germany
2. Clinic of Radiology, HELIOS Klinik Krefeld, Germany
3. Clinic for Plastic Surgery, HELIOS Klinik Krefeld, Germany
4. Institute for Medical Informatics, Biometry and Epidemiology, University Hospital Essen, Germany
5. Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, United States