1. State University of New York at Buffalo; Department of Medicine; ECMC CC-142 462 Grider Street Buffalo NY USA 14215
2. Norwegian Knowledge Centre for the Health Services; Global Health Unit; P.O. Box 7004, St. Olavs plass Oslo Norway N-0130
3. Yale University; Department of Medicine; New Haven USA
4. Norwegian Knowledge Centre for the Health Services; Prevention, Health Promotion and Organisation Unit; PO Box 7004 St Olavs Plass Oslo Norway 0130
5. National Cancer Institute Regina Elena; Department of Epidemiology; Via Elio Chianesi 53 Rome Italy 00144
6. University of Ottawa; Division of Infectious Diseases; Ottawa Ontario Canada
7. University of Toronto; Department of Psychiatry; 8th floor, Room 833 250 College Street Toronto Ontario Canada M5T 1R8
8. McMaster University; Department of Clinical Epidemiology and Biostatistics; 1200 Main Street West Hamilton Ontario Canada L8N 3Z5