Interferon beta and long-term disability in multiple sclerosis A Shirani, Y Zhao, ME Karim, C Evans, E Kingwell, ML {Van Der Kop}, J Oger, P Gustafson, J Petkau, H Tremlett January 2016 Source Document multiple-sclerosis observational-data Related Comparison of statistical approaches for dealing with immortal time bias in drug effectiveness studies Beta-interferon exposure and onset of secondary progressive multiple sclerosis Multiple sclerosis in older adults: the clinical profile and impact of interferon beta treatment 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