[1] Department for Health Services Research, Institute of Public Health and Nursing Research, University of Bremen, Grazer Straße 4, Bremen
[2] Health Sciences Bremen, University of Bremen, Bremen
[3] Institute of General Practice, Jena University Hospital, Bachstr. 18, Jena
[4] Institute of General Practice, Medical School Hannover, Carl-Neuberg-Str. 1, Hannover
[5] Institute of General Practice, Würzburg University Hospital, Joseph-Schneider-Str.2/D7, Würzburg
[6] Institute of General Practice, Göttingen University Hospital, Humboldtallee 38, Göttingen