1. Department of Epidemiology, Biostatistics and Occupational Health; McGill University; Montreal QC Canada
2. Department of Global Public Health and Primary Care; University of Bergen; Bergen Norway
3. Department of Neurology; Norwegian Multiple Sclerosis Competence Centre; Haukeland University Hospital; Bergen Norway
4. The KG Jebsen Centre for MS Research; Department of Clinical Medicine; University of Bergen; Bergen Norway
5. Department of Clinical and Experimental Medicine; University of Sassari; Sassari Italy
6. Department of Medicine; McGill University; Montreal QC Canada