1. Department of Public Health, Aarhus University, 8100 Aarhus C, Denmark
2. Research Unit for Epidemiology, Department of Public Health, Aarhus University, 8100 Aarhus C, Denmark
3. Department of Clinical Epidemiology, Aarhus University Hospital, 8100 Aarhus C, Denmark
4. The National Research Center for the Working Environment, Department of Public Health, University of Copenhagen, 2100 Copenhagen, Denmark
5. Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg University Hospital, 2400 Copenhagen NW, Denmark