
Multiple sclerosis is the most common disabling neurologic disease afflicting young adults in the United States. Since the majority of MS patients have normal or near-normal life expectancy, the clinical and economic burden is substantial, with disability typically worsening over time. Disease-modifying therapies have been shown to decrease and postpone long-term disability by lowering the relapse rate, extending the remission phase, and reducing the accumulation of new magnetic resonance imaging lesions and related neurologic deficits.