Journal of Clinical Epidemiology

Editors: A. Knottnerus Professor of General Practice, Netherlands School of Primary Care Research, President of the Scientific Council for Government Policy, Maastricht, The Netherlands, P. Tugwell Professor, Department of Medicine, Department of Epidemiology and Community Medicine; Canada Research Chair, Institute of Population Health, University of Ottawa, Ottawa, ON, Canada, Associate Editors: T. Dans Manila, Philippines, J. McGowan Ottawa, ON, Canada, M. Prins Maastricht, The Netherlands, G. Wells Ottawa, ON, Canada, Editorial Managers: K. Luyten Maastricht, The Netherlands, L. Fitzpatrick Ottawa, Canada, Assistant Editors: L. Idzerda Ottawa, Canada, D. Kotz Maastricht, The Netherlands, L. van Amelsvoort Maastricht, The Netherlands, Editor Emeritus: J. P. Vandenbroucke (Journal of Clincial Epidemiology) Leiden, The Netherlands , D. P. Earle (Journal of Chronic Diseases) Chicago, IL, USA, A. R. Feinstein New Haven, CT, USA, L. C. Lasanga Boston, MA, USA, W. O. Spitzer Kingston, ON, Canada, Policy Advisory Board: L. Bero San Francisco, CA, USA, M. Boers Amsterdam, The Netherlands, C. Bombardier Toronto, ON, Canada, P. Burney London, England, I. Dans Manila, Philippines, D. Grobbee Amsterdam, The Netherlands, G. Guyatt Hamilton, ON, Canada, F. E. Harrell, Jr. Nashville, TN, USA, R. Kane Minneapolis, MN, USA, D. Moher Ottawa, ON, Canada, A. O'Connor Ottawa, ON, Canada, M. S. Porta Barcelona, Spain, S. Straus Toronto, ON, Canada, Editorial Consultants Board: N.K. Arora New Delhi, India, F. Buntinx Leuven, Belgium, M. E. Charlson New York, NY, USA, J. Concato West Haven, CT, USA, R. De Vet Amsterdam, The Netherlands, J. G. Elmore Seattle, WA, USA, J. M. Esdaile Vancouver, BC, Canada, G. D. Eslick Boston, MA, USA, P. Glasziou Oxford, UK, G. B. Hill Rockland, ON, Canada, R. I. Horwitz Stanford, CA, USA, T. A. Hutchinson Montreal, PQ, Canada, J. Ioannidis Ioannina, Greece, L. Irwig Sydney, Australia, M. Jenicek Montreal, PQ, Canada, T. Kottke Minneapolis, MN, USA, L. H. Kuller Pittsburgh, PA, USA, M. A. D. Lansang Manila, Philippines, V. A. Lawrence San Antonio, TX, USA, S. R. Leeder Westmead, Australia, J. Lelorier Montreal, PQ, Canada, A. Liberati Modena, Italy, A. Morabia New York, NY, USA, P. Peduzzi West Haven, CT, USA, D. F. Ransohoff Chapel Hill, NC, USA, B. E. Rodda Austin, TX, USA, F. Rosendaal Leiden, The Netherlands, R. B. Shekelle Houston, TX, USA, M. van den Akker Maastricht, The Netherlands, D. van der Heijde Maastricht, The Netherlands, M. Weinberger Chapel Hill, NC, USA