Medical Department;
Sygehus Sφnderjylland Aabenraa;
DK-6200 Aabenraa;
Denmark;
Institute of Regional Health Services Research;
University of Southern Denmark;
DK-5000 Odense;
Denmark;
Department of Internal Medicine;
rebro University Hospital;
rebro University;
rebro 70185;
Sweden;
National Research Centre for the Working Environment;
DK-2100 Copenhagen;
Denmark;