title: Assessing Functional Decline in Neurological Diseases Clinical Trials: Duration of Follow-Up - The Case of Multiple Sclerosis.
abstract: BACKGROUND
  The main objective in the treatment of multiple sclerosis is to prevent or postpone the long-term disability caused by the disease, which in most cases occurs over years. However, most randomized clinical trials (RCTs) assessing the efficacy and safety of disease-modifying drugs have been designed to measure the short-term efficacy of disease-modifying drugs (up to 2-4 years) in reducing relapse rate and disease activity at magnetic resonance imaging (MRI).
  
  
  CONCLUSIONS
  In this chapter we will discuss how drug efficacy in reducing short-term relapse rate and MRI activity impact on delaying the accumulation of long-term disability, and we will summarize the available literature on the long-term efficacy of the drugs as assessed by the few long-term observational and long-term extension RCTs on available drugs, focusing on interferon-β treatment as the one with a more extensive literature.
  
  
  CONCLUSIONS
  Additional long-term observational studies and long-term extension of follow-up periods for patients included in RCTs are needed to explore the long-term efficacy of available drugs which are known to be effective at the short-term level.
authors.forename: Filippo
authors.initials: F
authors.lastname: Martinelli Boneschi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
mesh_terms: D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D017063:Outcome Assessment, Health Care; D016032:Randomized Controlled Trials as Topic / Q000379:methods*