1. Department of Metabolic and Bariatric Surgery, Slotervaart Hospital, Amsterdam, The Netherlands
2. Department of Surgery, Leiden University Medical Centre, Leiden, The Netherlands
3. Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre, Leiden, The Netherlands
4. Institute of Mathematics, Leiden University Medical Centre, Leiden, The Netherlands
5. Department of Surgery, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands