Author Affiliations: Division of Neurology and Brain Research Centre, Department of Medicine and Vancouver Coastal Health Research Institute (Drs Shirani, Evans, Kingwell, Oger, and Tremlett, and Ms van der Kop), Division of Neurology, Department of Medicine, MS/MRI Research Group (Dr Zhao), and Department of Statistics (Drs Gustafson and Petkau, and Mr Karim), University of British Columbia, Vancouver, Canada.
Greenberg et al1 highlighted our recent paper, which reported a “lack of evidence for a strong association between interferon beta treatment and disability progression.”2 This should not be interpreted as “interferon use does not prevent disability in patients with multiple sclerosis.”1 Nor does it seem appropriate to conclude that “the relapses prevented by interferon have been shown to lead to disability accumulation” by citing 2 short-term randomized clinical trials.3,4 It has become apparent that short-term effects may not translate into long-term benefits.5- 7 This is consistent with the observation that the association between relapses and disability progression diminishes over time.8
Shirani A, Zhao Y, Karim ME, Evans C, Kingwell E, van der Kop ML, Oger J, Gustafson P, Petkau J, Tremlett H. Interferon Beta and Long-term Disability in Multiple Sclerosis. JAMA Neurol. 2013;70(5):651-653. doi:10.1001/jamaneurol.2013.2197