An item response analysis of the international restless legs syndrome study group rating scale for restless legs syndrome

Glen R. Wunderlich, Kenneth R. Evans, Terrence Sills, Stephane Pollentier, Juergen Reess, Richard P. Allen, Wayne Hening, Arthur S. Walters, Charles Adler, Murat Aksu, Richard P. Allen, Melanie Anderson, Sonia Ancoli Israel, William Bara Jimenez, Claudio Bassetti, Donald L. Bliwise, Lauren L. Broch, David Buchholz, Sudhansun Chokroverty, Sandra ClavadetscherGiorgio Coccagna, Marco Tulio de Mello, Al W. de Weerd, Anjana Dhar, Bruce Ehrenberg, Ilonka Eisensehr, Karl Ekbom, Diego Garcia-Borreguero, Paul Gurecki, Mark Hallett, Wayne A. Hening, Linda Hirsch, Birgit Hogl, Jun Horiguchi, Magdolna Hornyak, Meir Kryger, Oscar Larrosa, Cheryl LeBrocq, Joseph F. Lipinski, Ake Ljungdahl, Elio Lugaresi, Ahmed Masood, Filomena Miele, Pasquale Montagna, Sarah Mosko, Stephanie Newman, Wolfgang H. Oertel, Shaun O'Keeffe, Alessandro Oldani, William G. Ondo, Barbara Phillips, Daniel Picchietti, Giuseppe Plazzi, J. Steven Poceta, Federica Provini, Cynthia Reiners, Gerald B. Rich, Roselyne M. Rijsman, Ray Rosen, David B. Rye, Larry Scrima, Renata Shafor, Denise Sharon, Michael Silber, Robert Skowrow, Robert Smith, Karin Stiasny, Claudia Trenkwalder, Sergio Tufik, Zebra Vanek, Ulrich Voderholzer, Mary Wagner, Thomas C. Wetter, Juliane Winkelmann, Rochelle Zak, Marco Zucconi

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34 Scopus citations


Background and purpose: Restless legs syndrome (RLS) is a common central nervous system disorder; however, there is currently a lack of well-validated and easily-administered measures of RLS severity available. The International Restless Legs Syndrome Study Group has recently developed a 10-item scale to meet this need. The International Restless Legs Severity Scale (IRLS) has been shown to have a high degree of reliability, validity, and internal consistency. In order to further demonstrate the validity of the IRLS, the present study examined the relationship between scores on individual IRLS items and overall RLS severity. Patients and methods: The 10-item IRLS was administered to 19 6 RLS patients. Option characteristic curves (the probability of scoring different options for a given item as a function of overall IRLS score) were generated in order to illustrate the scoring patterns for each item across the range of total RLS severity. Item characteristic curves (the expected score on an item as a function of overall IRLS score) were also generated to illustrate the relationship between scores on the individual items and total RLS severity. Results: The IRLS items demons trated excellent item response properties, with option and item characteristic curves closely approximating those of an ideal item. Item 3 (relief of arm or leg discomfort from moving around) was the most problematic item in that a 'floor' effect was evident; however, the item response characteristics for this item were still acceptable. Conclusions: Each IRLS item showed a good relationship between responses on that item and overall RLS severity, providing further evidence for the validity of the IRLS as a measure of RLS severity in RLS patients.

Original languageEnglish
Pages (from-to)131-139
Number of pages9
JournalSleep Medicine
Issue number2
StatePublished - Mar 2005
Externally publishedYes


  • Item response theory
  • RLS
  • Sleep disorders
  • Validation studies


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