title: Responsiveness of the EQ-5D and 8-item Parkinson's Disease Questionnaire (PDQ-8) in a 4-year follow-up study.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the responsiveness of the EQ-5D and the Parkinson's Disease Questionnaire (PDQ-8) to deterioration in health-related quality of life (HRQoL) in patients with Parkinson's disease (PD).
  
  
  METHODS
  HRQoL and clinical data collected from 31 patients with PD (male: 74.2%, mean age: 61 years) who were surveyed with the EQ-5D and the PDQ-8 questionnaires in 2002 and 2006/2007 were analyzed. Responsiveness of the EQ-5D, PDQ-8, and Hoehn and Yahr (H&Y) staging were assessed according to Cohen's effect size (ES) and standardized response mean (SRM).
  
  
  RESULTS
  The mean (standard deviation) EQ-5D index and PDQ-8 summary index (PDQ-8SI) scores were 0.76 (0.23) and 17.7 (14.2) at baseline and 0.52 (0.33) and 35.1 (17.4) at year four. Based on both ES and SRM indices, the rank order of responsiveness of the studied measures, from high to low, was PDQ-8SI (ES = 1.22), EQ-5D index score (ES = 1.06), H&Y score (ES = 0.82), and the EQ-VAS score (ES = 0.24).
  
  
  CONCLUSIONS
  Both the EQ-5D and PDQ-8 are responsive to changes in health burden of the Parkinson's disease over a 4-year period.
authors.affiliation: Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Block MD3, 16 Medical Drive, Singapore, 117597 Singapore. ephln@nus.edu.sg
authors.forename: Nan
authors.initials: N
authors.lastname: Luo
authors.forename: Wai-Yee
authors.initials: WY
authors.lastname: Ng
authors.forename: Puay-Ngoh
authors.initials: PN
authors.lastname: Lau
authors.forename: Wing-Lok
authors.initials: WL
authors.lastname: Au
authors.forename: Louis Cs
authors.initials: LC
authors.lastname: Tan
mesh_terms: D000223:Adaptation, Psychological; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010300:Parkinson Disease / Q000150:complications*; D011446:Prospective Studies; D011594:Psychometrics; D011788:Quality of Life; D013315:Stress, Psychological; D011795:Surveys and Questionnaires