1. Department of Epidemiology Research; Statens Serum Institut; Copenhagen Denmark
2. Danish Multiple Sclerosis Registry; Rigshospitalet; Copenhagen Denmark
3. Institute of Regional Health Research; University of Southern Denmark; Odense Denmark
4. Department of Neurology; Multiple Sclerosis Clinic of Southern Jutland (Sønderborg, Vejle, Esbjerg); Sønderborg Denmark
5. National Institute of Public Health; University of Southern Denmark; Copenhagen Denmark
6. Department of Clinical Epidemiology; Clinical Institute; University of Aarhus; Aarhus Denmark