Scoring the EQ-HWB-S: can we do it without value sets? A non-parametric item response theory analysis

• Published in: Quality of life research Vol. 33; no. 5; pp. 1211 - 1222
• Main Authors: Feng, You-Shan, Kohlmann, Thomas, Peasgood, Tessa, Engel, Lidia, Mulhern, Brendan, Pickard, A. Simon
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.05.2024; Springer Nature B.V
• Subjects: Adult; Aged; Australia; Female; Health care; Health economics; Humans; Item response theory; Male; Medicine; Medicine & Public Health; Middle Aged; Pharmacy; Preventive medicine; Psychometrics; Public Health; Quality of Life; Quality of Life Research; Quantitative psychology; Sociology; Surveys and Questionnaires; United Kingdom; United States; Australia; United States; United Kingdom; United Kingdom > UK; United States > US; Mokken scaling; EQ-HWB-S; Unweighted summary score; Non-preference scoring approaches; Level sum score; Non-parametric item response theory
• ISSN: 0962-9343; 1573-2649; 1573-2649
• DOI: 10.1007/s11136-024-03601-7

Background Only one pilot value set (UK) is currently available for the EQ Health and Wellbeing Instrument short version (EQ-HWB-S). As an alternative to preference-weighted scoring, we examined whether a level summary score (LSS) is appropriate for the EQ-HWB-S using Mokken scaling analyses. Methods Data from patients, carers and the general population collected during the developmental phase of the EQ-HWB-S in Australia, US and UK were used, noting 3 of 9 items have since undergone revision. EQ-HWB-S data fit was examined using R package Mokken scaling’s monotone homogeneity model, utilizing the automated item selection procedure (AISP) as well as Loevinger’s scaling coefficients for items and the scale (H S ). Manifest monotonicity was assessed by examining whether the cumulative probability for responses at or above each response level did not decrease across the summary score. Results EQ-HWB-S data were available for 3340 respondents: US = 903, Australia = 514 and UK = 1923. Mean age was 50 ± 18 and 1841 (55%) were female. AISP placed all 9 items of the EQ-HWB-S on a single scale when the lower bound was set to < 0.448. Strong scalability (H S  = 0.561) was found for the EQ-HWB-S as a single scale. Stronger scales were formed by separating the psychosocial items ( n  = 6, H S  = 0.683) and physical sensation items ( n  = 3, H S  = 0.713). No violations of monotonicity were found except for the items mobility and daily activities for the subgroups with long-term conditions and UK subjects, respectively. Discussion As EQ-HWB-S items formed a strong scale and subscales based on Mokken analysis, LSS is a promising weighting-free approach to scoring.