Long-term follow up of interferon-beta-1b pivotal trial RRMS patients: design issues of a 16-year follow-up study af Ebers, G, Rice, G, Traboulsee, A, Kaskel, P, Wolf, C, Salazar-Grueso, E

16-year long-term follow-up of interferon beta-1b treatment in patients with multiple sclerosis af Ebers, G, Rice, G, Wolf, C, Traboulsee, A, Langdon, D, Kaskel, P, Salazar-Grueso, E