[1] Univ Copenhagen, Fac Hlth & Med Sci, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
[2] Copenhagen Univ Hosp, Rigshosp, Dept Neurol, Danish Multiple Sclerosis Ctr, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
[3] Copenhagen Univ Hosp, Rigshosp, Danish Multiple Sclerosis Registry, Dept Neurol, Tagensvej 22, DK-2200 Copenhagen, Denmark
[4] Aarhus Univ Hosp, Dept Neurol, Palle Juul Jensens Blvd 99, DK-8200 Aarhus, Denmark