1. Danish Multiple Sclerosis Center, Department of Neurology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
2. The Danish Multiple Sclerosis Registry, Department of Neurology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
3. Department of Public Health, University of Copenhagen, Copenhagen, Denmark
4. Department of Clinical Immunology, Centre of Diagnostic Investigation, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark