1. Health Centre of the City of Helsinki, Helsinki, Finland;
2. Department of General Practice and Primary Health Care, University of Helsinki, Helsinki, Finland;
3. National Institute for Health and Welfare, Helsinki, Finland;
4. Department of General Practice and Primary Health Care, University of Helsinki and Helsinki University Hospital, Helsinki, Finland;
5. Folkhalsan Research Centre, Helsinki, Finland;
6. The Social Insurance Institution of Finland (KELA), Helsinki, Finland