1. Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
2. J.E. Cairnes School of Business & Economics, National University of Ireland, Galway, Ireland
3. The Comparative Health Outcomes, Policy, and Economics (CHOICE) Institute, University of Washington, Seattle
4. Center for Surgery and Health Economics, University of Pennsylvania, Philadelphia
5. Intensive Care National Audit & Research Centre (ICNARC), London, United Kingdom
6. Division of Medicine, University College London, London, United Kingdom