1. Neurosurgery, NeuroCenter, Kuopio University Hospital, Kuopio, Finland
2. Neurosurgery, Helsinki University Hospital, Helsinki, Finland
3. Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
4. Department of General Practice and Primary Health Care University of Helsinki, Helsinki, Finland
5. Department of Internal Medicine, Vasa Central Hospital, Vasa, Finland
6. Folkhälsan Research Centre, Helsinki, Finland
7. Unit of General Practice, Helsinki University Central Hospital, Helsinki, Finland