Multiple sclerosis in older adults: the clinical profile and impact of interferon beta treatment A Shirani, Y Zhao, J Petkau, P Gustafson, ME Karim, C Evans, E Kingwell, M L {Van Der Kop}, J Oger, H Tremlett January 2015 Source Document multiple-sclerosis longitudinal-data observational-data survival-analysis Related Beta-interferon exposure and onset of secondary progressive multiple sclerosis Investigation of heterogeneity in the association between interferon beta and disability progression in multiple sclerosis: an observational study Marginal structural Cox models for estimating the association between beta-interferon exposure and disease progression in a multiple sclerosis cohort Interferon beta and long-term disability in multiple sclerosis Association between use of interferon beta and progression of disability in patients with relapsing-remitting multiple sclerosis