title: Reliability and validity of two self-administered questionnaires for screening restless legs syndrome in population-based studies.
abstract: BACKGROUND
  A reliable and valid questionnaire for screening restless legs syndrome (RLS) is essential for determining accurate estimates of disease frequency. In a 2002 NIH-sponsored workshop, experts suggested three mandatory questions for identifying RLS in epidemiologic studies. We evaluated the reliability and validity of this RLS-NIH questionnaire in a community-based sample and concurrently developed and evaluated the utility of an expanded screening questionnaire, the RLS-EXP.
  
  
  METHODS
  The study was conducted at Kaiser Permanente of Northern California and the Stanford University Sleep Clinic. We evaluated test-retest reliability in a random sample of subjects with prior physician-assigned RLS (n=87), subjects with conditions frequently misclassified as RLS (n=31), and healthy subjects (n=9). Validity of both instruments was evaluated in a random sample of 32 subjects, and in-person examination by two RLS specialists was used as the gold standard.
  
  
  RESULTS
  For the first three RLS-NIH questions, the kappa statistic for test-retest reliability ranged from 0.5 to 1.0, and sensitivity and specificity was 86% and 45%, respectively. For the subset of five questions on RLS-EXP that encompassed cardinal features for diagnosing RLS, kappas were 0.4-0.8, and sensitivity and specificity were 81% and 73%, respectively.
  
  
  CONCLUSIONS
  Sensitivity of RLS-NIH is good; however, the specificity of the instrument is poor when examined in a sample that over-represents subjects with conditions that are commonly misclassified as RLS. Specificity can be improved by including separate questions on cardinal features, as used in the RLS-EXP, and by including a few questions that identify RLS mimics, thereby reducing false positives.
authors.affiliation: Dept. of Health Research & Policy, Division of Epidemiology, HRP Redwood Building, Room T209, Stanford University School of Medicine, Stanford, CA 94305-5405, USA. rpopat@stanford.edu
authors.forename: Rita A
authors.initials: RA
authors.lastname: Popat
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Van Den Eeden
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Tanner
authors.forename: Clete A
authors.initials: CA
authors.lastname: Kushida
authors.forename: Anil N
authors.initials: AN
authors.lastname: Rama
authors.forename: Jed E
authors.initials: JE
authors.lastname: Black
authors.forename: Allan
authors.initials: A
authors.lastname: Bernstein
authors.forename: Meike
authors.initials: M
authors.lastname: Kasten
authors.forename: Anabel
authors.initials: A
authors.lastname: Chade
authors.forename: Amethyst
authors.initials: A
authors.lastname: Leimpeter
authors.forename: John
authors.initials: J
authors.lastname: Cassidy
authors.forename: Valerie
authors.initials: V
authors.lastname: McGuire
authors.forename: Lorene M
authors.initials: LM
authors.lastname: Nelson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012148:Restless Legs Syndrome / Q000175:diagnosis*; D011795:Surveys and Questionnaires / Q000592:standards