title: Cross-cultural evaluation of the short form 8-item Parkinson's Disease Questionnaire (PDQ-8): results from America, Canada, Japan, Italy and Spain.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the psychometric properties of a short form health survey, the Parkinson's Disease Questionnaire (PDQ-8), cross-culturally, by comparing results gained from this instrument to the original longer form instrument-the PDQ-39.
  
  
  METHODS
  Data are from the Global Parkinson's Disease Survey.
  
  
  RESULTS
  The 8-item Parkinson's Disease Questionnaire Single Index Score (PDQ-8-SI). In this study, we evaluate response rate, scaling assumptions, and data quality, in terms of comparability of results with the parent form from which the PDQ-8 was derived, of the instrument in the USA, Canada, Spain, Italy and Japan.
  
  
  RESULTS
  The PDQ-8 was found to produce results that were very similar to the parent form across all five countries. However, it should be borne in mind that the PDQ-8 was nested within the PDQ-39, and results may be influenced by this.
  
  
  CONCLUSIONS
  Results suggest that the PDQ-8 is a valid and reliable measure that can be appropriately and meaningfully used in cross-cultural studies.
authors.affiliation: Department of Public Health, University of Oxford, Old Road Campus, Headington, Oxford OX3 7LF, UK. crispin.jenkinson@dphpc.ox.ac.uk
authors.forename: Crispin
authors.initials: C
authors.lastname: Jenkinson
authors.forename: Ray
authors.initials: R
authors.lastname: Fitzpatrick
mesh_terms: D000368:Aged; D002170:Canada; D003431:Cross-Cultural Comparison; D005260:Female; D006801:Humans; D007558:Italy; D007564:Japan; D008297:Male; D010300:Parkinson Disease / Q000523:psychology*; D011788:Quality of Life; D013030:Spain; D011795:Surveys and Questionnaires / Q000592:standards*; D014481:United States