1. Department of General Practice and Primary Health Care, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
2. Folkhälsan Research Center, Helsinki, Finland
3. Primary Health Care Unit, Kuopio University Hospital, , , Kuopio, Finland
4. Finnish Institute for Health and Welfare, Helsinki, Finland
5. Karolinska Institute, Stockholm, Sweden
6. Vantaa Health Centre, Vantaa, Finland