title: SF-36 includes less Parkinson Disease (PD)-targeted content but is more responsive to change than two PD-targeted health-related quality of life measures.
abstract: OBJECTIVE
  To compare validity including responsiveness, and internal consistency reliability and scaling assumptions of a generic (SF-36) and Parkinson Disease (PD)-targeted (PDQ-39; PDQUALIF) health-related quality of life (HRQOL) measures.
  
  
  METHODS
  Ninety-six PD patients were administered for all HRQOL measures by telephonic interview at baseline and 18 months. Relative efficiency and responsiveness were compared relative to four external criteria (self-ratings of PD's daily effects, global Quality of Life, PD symptom severity, and a depression screener). We examined whether PD-targeted measures explained unique variance beyond the SF-36 by regressing criterion variables on HRQOL scales/items. Adequacy of PD-targeted measures' original scaling was explored by item-scale correlations.
  
  
  RESULTS
  Relative efficiency estimates were similar for generic and PD-targeted measures across all criteria. Responsiveness analyses showed that the SF-36 yielded large (>0.8) effect sizes (ES) for three of eight scales for each of two criterion variables, compared to only one large ES for any scale in either PD-targeted measure. Adjusted R(2) increased from 14 to 27% in regression models that included PD-targeted items compared to models with only SF-36 scales. Item-scale correlations showed significant cross-loading of items across scales of the PD-targeted measures.
  
  
  CONCLUSIONS
  SF-36 responsiveness was better than that of two PD-targeted measures, yet those measures had content that significantly explains PD patients' HRQOL.
authors.affiliation: UCLA/VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Brown
authors.forename: Eric M
authors.initials: EM
authors.lastname: Cheng
authors.forename: Ron D
authors.initials: RD
authors.lastname: Hays
authors.forename: Stefanie D
authors.initials: SD
authors.lastname: Vassar
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Vickrey
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006304:Health Status; D006801:Humans; D007407:Interviews as Topic; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease; D011788:Quality of Life / Q000523:psychology*; D011795:Surveys and Questionnaires