title: From clinically relevant outcome measures to quality of life in epilepsy: A time trade-off study.
abstract: A proposed method for bridging the gap between clinically relevant epilepsy outcome measures and quality-adjusted life years is to derive utility scores for epilepsy health states. The aim of this study is to develop such a utility-function and to investigate the impact of the epilepsy outcome measures on utility.
  
  
  
  Health states, based on clinically important epilepsy attributes (e.g. seizure frequency, seizure severity, side-effects), were valued by a sample of the Dutch population (N=525) based on the time trade-off method. In addition to standard demographics, every participant was asked to rate 10 or 11 different health state scenarios. A multilevel regression analysis was performed to account for the nested structure of the data.
  
  
  
  Results show that the best health state (no seizures and no side-effects) is estimated at 0.89 and the worst state (seizures type 5 twice a day plus severe side-effects) at 0.22 (scale: 0-1). An increase in seizure frequency, occurrence of side-effects, and seizure severity were all significantly associated with lower utility values. Furthermore, seizure severity has the largest impact on quality of life compared with seizure frequency and side-effects.
  
  
  
  This study provides a utility-function for transforming clinically relevant epilepsy outcome measures into utility estimates. We advise using our utility-function in economic evaluations, when quality of life is not directly measured in a study and hence, no health state utilities are available, or when there is convincing empirical evidence of the insensitivity of a generic quality-of-life-instrument within epilepsy.
authors.affiliation: Department of Health Services Research, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands; Department of Research and Development, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands. Electronic address: Reina.dekinderen@maastrichtuniversity.nl.
authors.forename: Reina J A
authors.initials: RJ
authors.lastname: de Kinderen
authors.affiliation: Department of Health Services Research, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands; Department of Research and Development, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands.
authors.forename: Ben F M
authors.initials: BF
authors.lastname: Wijnen
authors.affiliation: Department of Methodology & Statistics, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands.
authors.forename: Gerard
authors.initials: G
authors.lastname: van Breukelen
authors.affiliation: Department of Research and Development, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands.
authors.forename: Debby
authors.initials: D
authors.lastname: Postulart
authors.affiliation: Department of Research and Development, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands; Department of Neurology, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands.
authors.forename: Marian H J M
authors.initials: MH
authors.lastname: Majoie
authors.affiliation: Department of Research and Development, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands; Department of Behavioral Sciences, Epilepsy Center Kempenhaeghe, Heeze, The Netherlands; MHENS School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
authors.forename: Albert P
authors.initials: AP
authors.lastname: Aldenkamp
authors.affiliation: Department of Health Services Research, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands; Trimbos Institute, Netherlands Institute of Mental Health and Addiction, Utrecht, The Netherlands.
authors.forename: Silvia M A A
authors.initials: SM
authors.lastname: Evers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003362:Cost-Benefit Analysis; D004827:Epilepsy / Q000150:complications / Q000175:diagnosis / Q000523:psychology* / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D017063:Outcome Assessment, Health Care; D011788:Quality of Life; D012044:Regression Analysis; D012640:Seizures / Q000150:complications / Q000175:diagnosis / Q000523:psychology / Q000628:therapy; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult
keywords: Cost-utility; Epilepsy; Preference-based; Quality of life; Time trade-off