Interferon Beta and Long-term Disability in Multiple Sclerosis

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