1. From the Institute of Neuroimmunology and Multiple Sclerosis (MH, JP, CH, ACR), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. private practice, Hamburg, Germany (MH)
3. Department of Neurology (CH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4. Nursing Research Unit, Institute of Social Medicine and Epidemiology, University of Lübeck, Lübeck, Germany (ACR)