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