title: Mapping algorithms from QLQ-C30 to EQ-5D utilities: no firm ground to stand on yet.
abstract: OBJECTIVE
  Over the last years several mapping or cross-walking algorithms for deriving utilities from QLQ-C30 scores have been published. However their external predictive accuracy has not yet been systematically compared.
  
  
  METHODS
  We tested the external validity of previously published mapping algorithms to transform the European Organization for Research and Treatment of Cancer QLQ-C30 questionnaire responses to EQ-5D derived Utilities.
  
  
  RESULTS
  When applied to different data sets, the currently published mapping showed a large variation between algorithms of the values of the mapped utilities, a low accuracy of the mapping compared to the observed EQ-5D utilities and no consistent performance between competing algorithms.
  
  
  CONCLUSIONS
  Therefore direct mapping from QLQ-C30 profiles to EQ-5D utilities using published algorithms should be viewed cautiously.
authors.affiliation: 1IRSS, Université Catholique de Louvain, Clos Chapelle aux Champs 30 bte 30.15, 1200, Brussels, Belgium.
authors.forename: Ralph
authors.initials: R
authors.lastname: Crott
mesh_terms: D000465:Algorithms; D006801:Humans; D009369:Neoplasms / Q000523:psychology* / Q000628:therapy; D011237:Predictive Value of Tests; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
keywords: EORTC; EQ-5D; QLQ-C30; cancer; cross-walking; mapping; preference; utility