title: Subscale assessment of the NEI-RQL-42 questionnaire with Rasch analysis.
abstract: OBJECTIVE
  To explore the psychometric properties of the 13 subscales of the NEI-RQL-42 questionnaire using Rasch analysis.
  
  
  METHODS
  The NEI-RQL-42 is a refractive error-related quality of life (QoL) questionnaire with a complex design; its 13 subscales contain 42 questions, which include 16 different question/response category formats. It was completed by 100 laser refractive surgery subjects (spectacle and contact lens wearers) pre- and postoperatively. Rasch analysis was used to assess the use of response categories, success in measuring a single trait per subscale (unidimensionality), ability to discriminate persons (precision), and targeting of the questions to person QoL.
  
  
  RESULTS
  Response categories were misused in four subscales (clarity of vision, diurnal fluctuation, symptoms, and appearance), which required repair before further analyses. Six subscales contained items that did not contribute to a single trait measurement (multidimensional). All subscales were found to be inadequate at distinguishing between persons (person separation >2.0), and targeting of the questions to QoL was poor for six subscales.
  
  
  CONCLUSIONS
  The NEI-RQL-42 questionnaire is deficient for all psychometric properties tested. Clinicians or researchers wishing to measure QoL related to refractive error correction should consider other questionnaires that have been rigorously developed and meet standard psychometric properties.
authors.affiliation: Department of Optometry and Vision Science, Flinders Medical Centre and Flinders University of South Australia, Bedford Park, South Australia, Australia.
authors.forename: Colm
authors.initials: C
authors.lastname: McAlinden
authors.forename: Eirini
authors.initials: E
authors.lastname: Skiadaresi
authors.forename: Jonathan
authors.initials: J
authors.lastname: Moore
authors.forename: Konrad
authors.initials: K
authors.lastname: Pesudovs
mesh_terms: D000328:Adult; D003261:Contact Lenses; D005260:Female; D006801:Humans; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D054554:National Eye Institute (U.S.) / Q000592:standards; D011594:Psychometrics / Q000379:methods* / Q000592:standards*; D011788:Quality of Life; D012030:Refractive Errors / Q000503:physiopathology / Q000523:psychology* / Q000628:therapy; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*; D014481:United States; D055815:Young Adult