1. Institute for Health Services Research and Health Economics; Centre for Health and Society; Faculty of Medicine; Heinrich-Heine University Düsseldorf; Düsseldorf Germany
2. mediStatistica; Neuenrade; Germany
3. AOK NordWest; Dortmund; Germany
4. Coordination Centre for Clinical Trials; Faculty of Medicine; Heinrich-Heine University Düsseldorf; Düsseldorf Germany
5. Department of Trauma and Hand Surgery; University Hospital Düsseldorf; Düsseldorf Germany