1. Research and Communication Unit for Musculoskeletal Health, Oslo University Hospital, Oslo, Norway.
2. Department of Neurology, Oslo University Hospital, Oslo, Norway.
3. Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway.
4. Department of Rheumatology, Østfold Hospital Trust, Grålum, Norway.
5. Division for Health Services, Norwegian Institute of Public Health, Oslo, Norway.
6. Faculty of Health Science, OsloMet – Oslo Metropolitan University, Oslo, Norway.
7. Department of Neurosurgery, University Hospital of Northern Norway, Tromsø, Norway.
8. Institute of Clinical Medicine, The Arctic University (UiT) of Norway, Tromsø, Norway.
9. Norwegian Registry for Spine Surgery (NORspine), University Hospital of Northern Norway, Tromsø, Norway.
10. Division of Clinical Neuroscience, Oslo University Hospital, Oslo, Norway.