1. The Danish Quality Unit of General Practice, Institute of Public Health, University of Southern Denmark, 5000 Odense, Denmark
2. The Research Unit of General Practice, Institute of Public Health, University of Southern Denmark, 5000 Odense, Denmark
3. Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institute, Clinical Epidemiology Unit T2, 17177 Stockholm, Sweden