1. Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark
2. Philip R. Lee Institute for Health Policy Studies, University of California, San Francisco
3. Department of Public Health, University of Copenhagen, Copenhagen, Denmark
4. Department of Epidemiology & Biostatistics, University of California, San Francisco
5. Clinical Excellence Research Center, Stanford University, Stanford, California
6. Department of Family & Community Medicine, University of California, San Francisco