title: Comparison of EQ-5D and SF-6D utilities in Pompe disease.
abstract: OBJECTIVE
  Comparative studies between Euroqol-5D (EQ-5D) and ShortForm 6D (SF-6D) utilities have been performed for a number of diseases, but not yet for orphan diseases. Pompe disease is an orphan disease with a prevalence of <5/10,000, characterized by impaired ambulatory and pulmonary functioning. We compared the psychometric properties of EQ-5D and SF-6D in patients with this disease and assessed their convergent validity, discriminative ability and sensitivity to change.
  
  
  METHODS
  EQ-5D utilities and SF-6D utilities were computed using the UK value set. Dimensions and utilities of the two instruments were compared by correlation coefficients and descriptive statistics. We assessed whether EQ-5D and SF-6D were able to discriminate between different levels of severity and examined sensitivity to change for patients with multiple observations.
  
  
  RESULTS
  Correlations between theoretically related dimensions of the EQ-5D and SF-6D were highly significant and were moderate to strong (range rho = 0.409-0.564). Utility values derived from the two instruments were similar (mean EQ-5D = 0.670; mean SF-6D = 0.699) and correlated strongly (rho = 0.591). Discriminative properties were somewhat better for EQ-5D; mean changes and effect sizes were better for SF-6D.
  
  
  CONCLUSIONS
  Overall, we conclude that both instruments appear to be equally appropriate with respect to assessing utilities in Pompe disease, but neither of them performed excellently. The descriptive system of the SF-6D describes health states for Pompe disease more accurately. EQ-5D showed better discriminative properties. The SF-6D performed better with respect to sensitivity to change.
authors.affiliation: Department of Health Policy and Management, Institute for Medical Technology Assessment, Erasmus University Rotterdam, Burgemeester Oudlaan 50, P.O. Box 1738, 3000, DR, Rotterdam, The Netherlands, kanters@bmg.eur.nl.
authors.forename: T A
authors.initials: TA
authors.lastname: Kanters
authors.forename: W K
authors.initials: WK
authors.lastname: Redekop
authors.forename: M E
authors.initials: ME
authors.lastname: Kruijshaar
authors.forename: A T
authors.initials: AT
authors.lastname: van der Ploeg
authors.forename: M P M H
authors.initials: MP
authors.lastname: Rutten-van Mölken
authors.forename: L
authors.initials: L
authors.lastname: Hakkaart
mesh_terms: D000328:Adult; D000368:Aged; D003362:Cost-Benefit Analysis; D005260:Female; D006009:Glycogen Storage Disease Type II / Q000473:pathology*; D006304:Health Status; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D011594:Psychometrics; D011788:Quality of Life; D035583:Rare Diseases / Q000473:pathology*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014797:Vital Capacity