title: Validation of the World Health Organization Disability Assessment Schedule II (WHODAS-II) in patients with multiple sclerosis.
abstract: BACKGROUND
  The World Health Organization Disability Assessment Schedule (WHODAS-II) is a widely used generic assessment instrument for health and disability. However, a specific psychometric evaluation for this scale in multiple sclerosis (MS) is lacking. This study is aimed at the assessment of the psychometric properties of the WHODAS-II in MS with Cronbach's α and modern Rasch-model analyses.
  
  
  METHODS
  The WHODAS-II was administered to 136 consecutively recruited MS patients. Several indexes of fit to the Rasch model were evaluated in order to assess internal construct validity. Internal consistency was assessed with Cronbach's α and the Person Separation Index (PSI). External validity was evaluated by analyzing correlations between the WHODAS-II and the Multiple Sclerosis Quality of Life-54 (MSQoL-54).
  
  
  RESULTS
  Classical reliability indexes (Cronbach's α and intraclass correlation) showed good to excellent reliability for most of the subscales and for the total scale (α = 0.93). The total scale both with (36 items) or without (32 items) work items reached good fit to the Rasch model (PSI = 0.83). However, analysis of the subscales could resolve only four subscales out of seven.
  
  
  CONCLUSIONS
  The WHODAS-II is a reliable and valid instrument for the assessment of patient-reported disability in MS, with some limitations including some item redundancy and questionable reliability of some subscales.
authors.affiliation: Neurology and NeuroRehabilitation Unit, Fondazione IRCCS Santa Lucia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magistrale
authors.affiliation: Neurology and NeuroRehabilitation Unit, Fondazione IRCCS Santa Lucia, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: Pisani
authors.affiliation: Neurology and NeuroRehabilitation Unit, Fondazione IRCCS Santa Lucia, Italy.
authors.forename: Ornella
authors.initials: O
authors.lastname: Argento
authors.affiliation: Neurology and NeuroRehabilitation Unit, Fondazione IRCCS Santa Lucia, Italy.
authors.forename: Chiara C
authors.initials: CC
authors.lastname: Incerti
authors.affiliation: Neuroimaging Laboratory, Fondazione IRCCS Santa Lucia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bozzali
authors.affiliation: Neurology Clinical Development Group, Biogen Idec, USA.
authors.forename: Diego
authors.initials: D
authors.lastname: Cadavid
authors.affiliation: Neurology and NeuroRehabilitation Unit, Fondazione IRCCS Santa Lucia, Italy/University of Rome "Tor Vergata", Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Caltagirone
authors.affiliation: Neurology Clinical Development Group, Biogen Idec, USA.
authors.forename: Rossella
authors.initials: R
authors.lastname: Medori
authors.affiliation: Kessler Foundation, USA/Rutgers, New Jersey Medical School, USA.
authors.forename: John
authors.initials: J
authors.lastname: DeLuca
authors.affiliation: Neurology and NeuroRehabilitation Unit, Fondazione IRCCS Santa Lucia, Italy/University of Rome "Tor Vergata", Italy u.nocentini@hsantalucia.it.
authors.forename: Ugo
authors.initials: U
authors.lastname: Nocentini
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications*; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D014944:World Health Organization
keywords: Multiple sclerosis; Rasch analysis; disability; patient-reported outcomes; psychometric assessment; reliability