OBJECTIVES: The Weight-Specific Adolescent Instrument for Economic Evaluation (WAItE) is a weight-specific Health-Related Quality of Life (HRQoL) measure, containing seven dimensions with five severity levels. Two valuation studies (in the UK and Australia) have recently been conducted. This study aimed to compare the preferences from these valuation studies.

METHODS: Discrete Choice Experiments (DCEs) were conducted with adults in the UK (n=1,005) and Australia (n=1,005). DCE data were analysed using a mixed logit model. The interim UK value set was anchored onto the Quality Adjusted Life Year (QALY) scale using an external Time Trade-Off (TTO) study and the visual analogue scale (VAS). The interim Australian value set was anchored onto the QALY scale using the VAS method and the ‘Comparisons with Death’ (CWD) approach. Relative Attribute Importance (RAI) scores were calculated for both samples.

RESULTS: Inconsistencies were observed for certain dimensions in both the UK and Australian samples, and therefore some levels were combined to ensure monotonicity within dimensions. RAI scores showed the same dimension was valued as the least important in both samples, however, the most important dimensions differed. In the UK sample, the different anchoring methods generated similar value sets. Values for the ‘PITS state’ (the worst health state possible from the WAItE classification system) were 0.230 and 0.289 using the TTO and VAS anchoring methods respectively. Conversely, the interim value sets generated using each anchoring method in the Australian sample were quite different, as the values for the PITS state were quite different. The values for the PITS state were 0.429 and -0.030 when using the VAS and CWD anchoring methods respectively.

CONCLUSIONS: The UK and Australian interim value sets for the WAItE display several similarities, yet the values for the PITS state are not comparable. The choice of anchoring approach influences the results in both samples.