1. Department of General Practice and Health Services Research, Heidelberg University Hospital, Heidelberg, Germany;
2. AQUA Institute for Applied Quality Improvement and Research in Health Care, Goettingen, Germany;
3. Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany;
4. Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany