title: Mapping EQ-5D utility scores from the Incontinence Quality of Life Questionnaire among patients with neurogenic and idiopathic overactive bladder.
abstract: OBJECTIVE
  To provide a mapping algorithm for estimating EuroQol five-dimensional (EQ-5D) questionnaire index scores from the Incontinence-specific Quality of Life questionnaire (I-QOL) based on nationally representative samples of patients with idiopathic or neurogenic overactive bladder (OAB) using EQ-5D questionnaire preference valuations based on both the UK and US general populations.
  
  
  METHODS
  Analyses were conducted for 2505 patients from the Adelphi Overactive Bladder Disease Specific Programme, a cross-sectional study of patients with idiopathic or neurogenic OAB, undertaken in the United States and Europe in 2010. A range of statistical modeling techniques was used. Tenfold cross-validation techniques were used to calculate mean absolute error (MAE) and root mean squared error (RMSE) goodness-of-fit statistics. Various predictor lists, together with a method combining stepwise selection with multivariable fractional polynomial techniques to allow nonlinear relationships to feature, were pursued.
  
  
  RESULTS
  Choice of predictors was consistent for both the UK and US EQ-5D questionnaire tariffs. For idiopathic, the best model included the I-QOL total score and age (both modeled nonlinearly.) For neurogenic, the best model was the I-QOL social embarrassment domain score modeled linearly only. Best-fit results were better in the idiopathic (n = 2351; MAE = 0.10; RMSE = 0.14) than in the neurogenic sample (n = 254; MAE = 0.17; RMSE = 0.22).
  
  
  CONCLUSIONS
  This research provides algorithms for mapping EQ-5D questionnaire index scores from the I-QOL, allowing calculation of appropriate preference-based health-related quality-of-life scores for use in cost-effectiveness analyses when only I-QOL data are available. The strongest results were for idiopathic patients, but those for neurogenic are consistent with those of other published mapping studies.
authors.affiliation: Adelphi Real World, Macclesfield, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Kay
authors.forename: Keith
authors.initials: K
authors.lastname: Tolley
authors.forename: Danielle
authors.initials: D
authors.lastname: Colayco
authors.forename: Kristin
authors.initials: K
authors.lastname: Khalaf
authors.forename: Peter
authors.initials: P
authors.lastname: Anderson
authors.forename: Denise
authors.initials: D
authors.lastname: Globe
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D005602:France; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000295:instrumentation*; D019057:Quality-Adjusted Life Years; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D013030:Spain; D011795:Surveys and Questionnaires; D006113:United Kingdom; D014481:United States; D053201:Urinary Bladder, Overactive / Q000523:psychology*; D014549:Urinary Incontinence / Q000523:psychology*