1. Institute of Social Medicine, University of Lübeck, Lübeck, Germany
2. Department of Health and Caring Sciences, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
3. Neurological Rehabilitation Center Quellenhof, Bad Wildbad, Germany
4. Department of Neurology, Segeberger Kliniken, Bad Segeberg, Germany
5. Department of Therapeutic Sciences, MSH Medical School Hamburg, Hamburg, Germany
6. RehaCentre Hamburg, Hamburg, Germany
7. Unit of Health Sciences and Education, MIN Faculty, University of Hamburg, Hamburg, Germany
8. Institute of Neuroimmunology & Multiple Sclerosis and Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
9. Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany