Validity and test-retest reliability of a disability questionnaire for essential tremor

Elan D. Louis, Livia F. Barnes, Kristin J. Wendt, Steven M. Albert, Seth L. Pullman, Qiping Yu, Franklin R. Schneier

Research output: Contribution to journalArticle

Abstract

Background: One important outcome in clinical trials is patients' own opinions about whether the medication alleviates their symptoms and improves their ability to function. A valid and reliable method with which to assess this subjective information is important. Objective: To determine the validity and test-retest reliability of the Columbia University Disability Questionnaire for Essential Tremor (ET). Methods: Patients with ET underwent a 2.5-hour evaluation, including a 36-item tremor disability questionnaire, to assess the functional impact of tremor, a 26-item videotaped tremor examination rated by a neurologist, a 15-item performance-based test, and quantitative computerized tremor analysis. We determined the validity and test-retest reliability of the tremor disability questionnaire. Correlations between variables were assessed using Pearson's correlation coefficients and test-retest reliability with the weighted kappa statistic. Results: Ninety-five patients with ET participated. The score on tremor disability questionnaire correlated with the neurologist's clinical ratings (r = 0.57, p <0.001) and the total score on the performance-based test (r = 0.69, p <0.001). Correlations with quantitative computerized tremor analysis results were less robust, but each remained significant, including mean amplitude of dominant arm tremor while arms were extended (r = 0.56, p <0.001), while drawing a spiral (r = 0.42, p = 0.01), and while pouring (r = 0.34, p = 0.04). The questionnaire was readministered to 32 subjects, and the test-retest reliability was substantial (weighted kappa = 0.67). Conclusions: This Tremor Disability Questionnaire demonstrated substantial reliability, and it correlated with multiple measures of tremor severity, including a neurologist's clinical ratings, a performance-based test of function, and quantitative computerized tremor analysis results. The questionnaire would be useful in clinical trials in which it could be used as a reliable and valid tool to assess disability in ET.

Original languageEnglish (US)
Pages (from-to)516-523
Number of pages8
JournalMovement Disorders
Volume15
Issue number3
DOIs
StatePublished - Jun 17 2000
Externally publishedYes

Keywords

  • Disability
  • Essential tremor
  • Questionnaire
  • Reliability
  • Validity

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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