1. University Medical Centre Mannheim, University of Heidelberg; Department of Surgery; Theodor-Kutzer-Ufer 1-3 Mannheim Baden-Württemberg Germany 68167
2. Medical Center - University of Freiburg; Institute for Evidence in Medicine (for Cochrane Germany Foundation); Breisacher Straße 153 Freiburg Germany 79110
3. Institute of General Practice, Medical Faculty of the Heinrich-Heine-University Düsseldorf; Cochrane Metabolic and Endocrine Disorders Group; Moorenstr. 5 Düsseldorf Germany 40225