1. Centre for Health Economics; University of York; York UK
2. Department of Health Sciences; University of York; York UK
3. Division of Epidemiology and Biostatistics; University of Leeds; UK
4. Department of Cardiothoracic Surgery; University Hospital Birmingham Queen Elizabeth; Edgbaston UK
5. Department of Cardiovascular Surgery; Hospital Clinic de Barcelona; Barcelona Spain
6. Institute for Health Sciences; IIS Aragón; Zaragoza Spain