1. Department of Public Health; University of Copenhagen; Copenhagen K Denmark
2. Group Health Research Institute; Seattle WA, USA
3. Department of Epidemiology and Biostatistics; University of California; San Francisco CA, USA
4. General Internal Medicine Section, Department of Veterans Affairs; University of California; San Francisco CA, USA
5. Center of Diagnostic Imaging; Copenhagen University Hospital; Rigshospitalet; Denmark
6. Department of Surgery; University of Vermont; Burlington VT, USA