1. Department of Primary Medical Care, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Institute of General Practice, Medical Faculty, University of Kiel, Kiel, Germany
3. Department of Psychiatry, Technical University Munich, Munich, Germany
4. Institute of General Practice, University Düsseldorf, Düsseldorf, Germany
5. Institute of General Practice, University Hospital Jena, Jena, Germany
6. Institute of General Practice and Family Medicine, University Hospital of Ludwig-Maximilians-University Munich, München, Germany
7. Department of Psychiatry and Psychotherapy, University Bonn, Bonn, Germany
8. Institute for Social Medicine, Occupational Health and Public Health, University Leipzig, Leipzig, Germany
9. Department of Health Economics and Health Services Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
10. Institute of General Practice, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
11. Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
12. Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
13. Institute of General Practice, WG Medical Statistics and IT-Infrastructure, Hannover Medical School, Hannover, Germany