Abstract
Methods
The validity of individual questionnaire items is studied using an Item Response/Latent Trait Theory modeling approach. Sensitivity
of response patterns on EQ-5D items to particular diagnostic subtypes of psychosis is investigated using a finite mixture
modeling approach through latent class analysis. Finally, a structural equation modeling framework is used to study differential
item functioning via a multigroup approach.
of response patterns on EQ-5D items to particular diagnostic subtypes of psychosis is investigated using a finite mixture
modeling approach through latent class analysis. Finally, a structural equation modeling framework is used to study differential
item functioning via a multigroup approach.
Results
Results suggest that the data closely correspond to the Rasch Rating Scale Model, and therefore that EQ-5D latent scores are
equal interval measures. Despite comprising relatively few items, the instrument yields reliable measures of HRQoL for group
comparisons and cost-effectiveness evaluation, but EQ-5D score is too imprecise for the assessment of HRQoL for clinical purposes
at the individual level. A significant relationship was found between EQ-5D responses and type of psychosis due to inclusion
of item anxiety/depression in EQ-5D. Two items (anxiety/depression, functioning in usual activities) showed an ethnicity bias.
equal interval measures. Despite comprising relatively few items, the instrument yields reliable measures of HRQoL for group
comparisons and cost-effectiveness evaluation, but EQ-5D score is too imprecise for the assessment of HRQoL for clinical purposes
at the individual level. A significant relationship was found between EQ-5D responses and type of psychosis due to inclusion
of item anxiety/depression in EQ-5D. Two items (anxiety/depression, functioning in usual activities) showed an ethnicity bias.
- Content Type Journal Article
- Pages 1-9
- DOI 10.1007/s11136-012-0222-7
- Authors
- J. Stochl, Department of Psychiatry, Addenbrookes Hospital, University of Cambridge, Box 189, Cambridge, CB2 0QQ UK
- T. Croudace, Department of Psychiatry, Addenbrookes Hospital, University of Cambridge, Box 189, Cambridge, CB2 0QQ UK
- J. Perez, Department of Psychiatry, Addenbrookes Hospital, University of Cambridge, Box 189, Cambridge, CB2 0QQ UK
- M. Birchwood, School of Psychology, University of Birmingham, Edgbaston, Birmingham, B15 2TT UK
- H. Lester, School for Primary Care Research, National Institute for Health Research, University of Manchester, Manchester, M13 9PL UK
- M. Marshall, School of Medicine, University of Manchester, Manchester, M13 9PT UK
- T. Amos, Department of Psychiatry, University of Bristol, Bristol, BS8 2BN UK
- V. Sharma, Cheshire and Wirral Partnership NHS Foundation Trust, Preston, PR2 8DY UK
- D. Fowler, Department of Medicine, Health Policy, and Practice, University of East Anglia, Norwich, NR4 7TJ UK
- P. B. Jones, Department of Psychiatry, Addenbrookes Hospital, University of Cambridge, Box 189, Cambridge, CB2 0QQ UK
- The National Eden Study Team
- Journal Quality of Life Research
- Online ISSN 1573-2649
- Print ISSN 0962-9343