Affiliation: | 1. Departments of Surgery, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands;2. Department of Surgery, Groene Hart Ziekenhuis, Gouda, The Netherlands;3. Departments of Epidemiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands;4. Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK |