1. Department of Surgery (Division of Vascular Surgery), University Medical Center Groningen , Hanzeplein 1, Groningen 9713 GZ, The Netherlands
2. Department of Cardiothoracic Surgery, Leiden University Medical Center , Albinusdreef 2, Leiden 2333 ZA, The Netherlands
3. Department of Cardiothoracic Surgery, Amsterdam University Medical Center , Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands
4. Knowledge Institute of Medical Specialists , Mercatorlaan 1200, Utrecht 3528 BL, The Netherlands
5. Cochrane Netherlands/Julius Center for Health Sciences and Primary Care, University, Utrecht Medical Center , Heidelberglaan 100, Utrecht, 3584 CX, The Netherlands