1. Department of Health Services Research, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
2. Institute for Social Medicine and Epidemiology, Nursing Research Unit, University of Lübeck, Germany
3. Medical Faculty, Institute for Health and Nursing Science, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
4. Center for Health Economics and Health Services Research, Schumpeter School of Business and Economics, University of Wuppertal, Wuppertal, Germany
5. mediStatistica, Wuppertal, Germany
6. Institute for General Practice, Hannover Medical School, Hannover, Germany
7. Institute of Nursing Sciences, University of Cologne, Medical Faculty and University Hospital Cologne, Cologne, Germany