1. Department of Public Health, Aarhus University, Aarhus, Denmark
2. Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA
3. Winship Cancer Institute, Emory University, Atlanta, GA, USA
4. Department of Population Health Sciences, Duke University, Durham, NC, USA
5. Department of Health Management and Health Economics, Oslo University, Oslo, Norway
6. Clinical effectiveness research group, Oslo University Hospital, Oslo, Norway