1. Research Unit of General Practice, Institute of Public Health, University of Southern Denmark , J.B. Winsløws vej 9A, 5000 Odense C , Denmark
2. The Research Unit for General Practice, Department of Public Health, University of Copenhagen , Øster Farimagsgade, 1014 København K , Denmark
3. Danish Centre for Health Economics—DaCHE, Institute of Public Health, University of Southern Denmark , J.B. Winsløws vej 9A, 5000 Odense C , Denmark