Measuring the rate of progression in friedreich ataxia: Implications for clinical trial design

Lisa S. Friedman, Jennifer M. Farmer, Susan Perlman, George Wilmot, Christopher M. Gomez, Khalaf O. Bushara, Katherine D. Mathews, S. H. Subramony, Tetsuo Ashizawa, Laura J. Balcer, Robert B. Wilson, David R. Lynch

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


Friedreich ataxia is an autosomal recessive neurodegenerative disorder characterized by ataxia of all four limbs, dysarthria, and arreflexia. A variety of measures are currently used to quantify disease progression, including the Friedreich Ataxia Rating Scale, examiner-rated functional disability scales, self-reported activities of daily living and performance measures such as the timed 25-foot walk, 9-hole pegboard test, PATA speech test, and low-contrast letter acuity vision charts. This study examines the rate of disease progression over one and two years in a cohort of 236 Friedreich ataxia patients using these scales and performance measure composites. The Friedreich Ataxia Rating Scale and performance-measure composites captured disease progression, with a greater sensitivity to change over 2 years than over 1 year. The measures differed in their sensitivity to change and in possible bias. These results help to establish norms for progression in FRDA that can be useful in measuring the long-term success of therapeutic agents and defining sample-size calculations for double-blind clinical trials.

Original languageEnglish (US)
Pages (from-to)426-432
Number of pages7
JournalMovement Disorders
Issue number4
StatePublished - Mar 15 2010


  • Ataxia
  • Clinical neurology examination
  • Mitochondrial disorder
  • Natural history study
  • Trinucleotide repeat disease

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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