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Performance measures in Friedreich ataxia: Potential utility as clinical outcome tools

Authors

  • David R. Lynch MD, PhD,

    Corresponding author
    1. Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
    2. Department of Pediatrics, University of Pennsylvania School of Medicine, and Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
    • Division of Neurology, Children's Hospital of Philadelphia, 502 Abramson Building, Philadelphia, PA 19104-4318
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  • Jennifer M. Farmer MSGC,

    1. Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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  • Robert L. Wilson MD, PhD,

    1. Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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  • Laura J. Balcer MD, MSCE

    1. Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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Abstract

Although several neuroprotective agents have been proposed as potential therapies in Friedreich ataxia (FA), clinical trials of their efficacy are limited by a lack of sensitive outcome measures. We assessed whether performance measures (nine-hole peg test, the timed 25-foot walk, and low-contrast letter acuity) provide valid measures of disease status in FA. Scores for each measure correlated significantly with neurologic disability and disease duration. Rank correlations between scores for performance measures were moderate in magnitude, suggesting that the each test captures separate yet related dimensions of neurological function in FA. Linear regression models demonstrated that scores from the nine-hole peg test and the timed 25-foot walk (after reciprocal transformation) were predicted by age and triplet repeat length in patients with FA. In addition, comparison of the temporal courses of change for each performance measure demonstrated that scores from the timed 25-foot walk change early in the course of FA, nine-hole peg test scores change slowly over the full course of the disorder, and low-contrast letter acuity scores change in the later stages of the disease. Thus, a composite scale derived from these performance measures may provide the best overall measure for assessing disease progression throughout the illness. © 2005 Movement Disorder Society

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