1. Institute of Family Medicine, University Hospital Schleswig-Holstein Campus, Ratzeburger Allee 160, Haus 50, Luebeck, Germany
2. EQUAM-Stiftung, Effingerstrasse 25, Bern, Switzerland
3. Institute of General Practice and Health Services Research, University of Zurich, Pestalozzistrasse 24, Zürich, Switzerland
4. aQua-Institute for Applied Quality Improvement and Research in Health Care, Maschmühlenweg 8-10, Goettingen, Germany