A UK value set for the WAItE.

Objectives: The Weight-Specific Adolescent Instrument for Economic Evaluation (WAItE) is a weight-specific patient reported outcome measure for use in adolescence, consisting of seven domains, each with five response levels. The objective of this study was to generate a UK value set for the WAItE, enabling the calculation of utility values.

Methods: An online Discrete Choice Experiment (DCE) completed by an adult sample representative to the working population of the UK was used to estimate the preferences for the five levels of the seven domains. DCE data were analysed using Multinomial and Mixed Logit models. The latent values were then anchored onto the 0-1 death-full health Quality Adjusted Life Year (QALY) scale using two different anchoring techniques, the Time Trade Off (TTO) method and the DCE-Visual Analogue Scale (DCE-VAS) method.

Results: 1,004 adults from the UK were included in the final estimation sample for the DCE. From the latent estimates, the majority of the levels of the dimensions followed the monotonic nature of the WAItE, however some levels of the 'Tiredness', 'Walking' and 'Sports' related dimensions were not monotonic and combined to generate the final value set. The results from the TTO and DCE-VAS anchoring methods were similar, with values for the 'PITS state' (the worst health state possible from the WAItE) of 0.289 and 0.230.

Conclusions: This study has developed a value set for the WAItE based on the preferences of the UK population, enabling the use of the WAItE in cost utility analyses of interventions targeting obesity in adolescents.