1. Harvard Medical School/Harvard Pilgrim Health Care, Department of Ambulatory Care & Prevention, Boston, MA
2. Schering-Plough Corporation, Kenilworth, NJ
3. Tufts-New England Medical Center, Institute for Clinical Research and Health Policy, Boston, MA, USA
4. Janssen-Cilag Ltd, High Wycombe, UK and 5Boston Health Economics, Waltham, MA, USA