1. University Spine Centre Zurich, University Hospital Balgrist, University of Zurich, Zurich, Switzerland
2. Horten Centre for Patient Oriented Research and Knowledge Transfer, University of Zurich, Zurich, Switzerland
3. Institute of Primary Care, University and University Hospital Zurich, Zurich, Switzerland
4. Department of Orthopedics and Neurosurgery, Spine Center, Schulthess Clinic, Zurich, Switzerland
5. Division of General Internal Medicine, Bern University Hospital, Bern University, Bern, Switzerland
6. for the Lumbar Stenosis Outcome Study Group