1. Danish Multiple Sclerosis Center, Department of Neurology, Rigshospitalet, Copenhagen, Denmark/University of Copenhagen, Copenhagen, Denmark
2. National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
3. The Danish Multiple Sclerosis Registry, Rigshospitalet, Copenhagen, Denmark/Department of Clinical Epidemiology, Clinical Institute, Aarhus University, Aarhus, Denmark
4. Paediatric Department, Hvidovre Hospital, Hvidovre, Denmark/Departments of Public Health and Science in Nursing, Aarhus University, Aarhus, Denmark
5. Danish Multiple Sclerosis Center, Department of Neurology, Rigshospitalet, Copenhagen, Denmark/The Danish Multiple Sclerosis Registry, Rigshospitalet, Copenhagen, Denmark