1. School of Social Sciences, University of Applied Sciences Saarbrücken, Saarbrücken, Germany
2. University of Cooperative Education in Health Care and Welfare Saarland, Saarbrücken, Germany
3. Institute for Evidence in Medicine (for Cochrane Germany Foundation), Faculty of Medicine and Medical Center, University of Freiburg, Breisgau, Germany
4. Centre of Geriatric Medicine and Gerontology Freiburg, Faculty of Medicine and Medical Center, University of Freiburg, Breisgau, Germany