title: Validation and comparison of 15-D and EQ-5D-5L instruments in a Spanish Parkinson's disease population sample.
abstract: OBJECTIVE
  To contribute to the ongoing discussion on the choice of a preference-based health-related quality of life (HRQoL) instrument to be used in cost-effectiveness analysis by studying and comparing the validity, sensitivity and relative efficiency of 15-D and EuroQol 5D 5L (EQ-5D-5L) in a Spanish Parkinson's disease (PD) population sample.
  
  
  METHODS
  One hundred and thirty-three volunteers were asked to complete an interview using 15-D and EQ-5D-5L. Spearman's rank correlation coefficient (r) was used to test the convergent validity of these instruments with specific PD measures. Sensitivity and efficiency were compared using receiver operating characteristic (ROC) curves and relative efficiency statistic, respectively.
  
  
  RESULTS
  A strong correlation (r > 0.65; p < 0.001) was found between both 15-D and EQ-5D-5L utilities with the summary score of the PDQ-8, and a strong correlation (r > 0.50; p < 0.001) was found between 15-D and EQ-5D-5L utilities with the EQ-VAS. The areas under the ROC of both instruments all exceeded 0.5 (p < 0.001). The 15-D instrument was 4.1-29.8 % less efficient at detecting differences between patients with optimal HRQoL, while this instrument was 11 % more efficient at detecting differences between patients at mild and moderate to strong severity of the PD symptoms.
  
  
  CONCLUSIONS
  15-D and EQ-5D-5L are showed to be valid and sensitivity generic HRQoL measures in Spanish PD patients with both instruments showing similar HRQoL dimension coverage and ceiling/floor effects. The 15-D has better efficiency and greater sensitivity to detect clinical changes in PD severity of the symptoms meanwhile the EQ-5D-5L is better to detect clinical HRQoL changes. Additionally, the EQ-5D-5L questionnaire requires less time than 15-D to be administered, and it might be more appropriate for studies conducted in Spain, since a country-specific "value set" is available for this instrument and not for the 15-D.
authors.affiliation: Department of Applied Economics, Faculty of Economics and Business, University of Murcia, Campus de Espinardo s/n, 30100, Murcia, Spain, miguelgarciagordillo@gmail.com.
authors.forename: Miguel  Ángel
authors.initials: M
authors.lastname: García-Gordillo
authors.forename: Borja
authors.initials: B
authors.lastname: del Pozo-Cruz
authors.forename: José Carmelo
authors.initials: JC
authors.lastname: Adsuar
authors.forename: Fernando Ignacio
authors.initials: FI
authors.lastname: Sánchez-Martínez
authors.forename: José María
authors.initials: JM
authors.lastname: Abellán-Perpiñán
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003362:Cost-Benefit Analysis; D003430:Cross-Sectional Studies; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000191:economics / Q000523:psychology*; D011159:Population Surveillance; D011237:Predictive Value of Tests; D011594:Psychometrics / Q000295:instrumentation* / Q000379:methods; D011788:Quality of Life; D012372:ROC Curve; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D013030:Spain; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires