1. Royal Brompton Hospital, London, UK
2. Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, UK
3. Medical Statistics Department, London School of Hygiene and Tropical Medicine, London, UK
4. Birmingham Children’s Hospital, Birmingham, UK
5. Southampton General Hospital, Southampton, UK
6. Faculty of Medicine and Health, University of Leeds, Leeds, UK
7. Boston Children’s Hospital, Boston, MA, USA
8. Alder Hey Hospital, Liverpool, UK
9. Great Ormond Street Hospital for Children, London, UK
10. Glenfield Hospital and Leicester Royal Infirmary, Leicester, UK
11. Royal Manchester Children’s Hospital, Manchester, UK
12. St Mary’s Hospital, London, UK
13. University Hospital of North Staffordshire, Stoke-on-Trent, UK
14. Bristol Royal Hospital for Children, Bristol, UK