The Recovering Quality of Life – Utility Index (ReQoL-UI): the Hong Kong valuation study

This study aims to establish a Hong Kong (HK)-specific value set for the ReQoL-UI, an instrument designed to evaluate health-related quality of life with a focus on mental health, using the discrete choice experiment-time trade-off approach to facilitate cost-utility analyses of mental health interventions. A web-based survey was conducted from April to August 2024, recruiting 1,008 HK residents aged 20–69 years. Quota sampling was used to ensure age and sex representativeness based on 2021 HK census data. The ReQoL-UI’s seven dimensions with a duration item were evaluated across 180 choice sets divided into 15 blocks, with participants completing 12 tasks each. Utility weights were estimated using a conditional logit and mixed logit models, anchored to a 1 (full health) to 0 (dead) scale, and refined for consistency and statistical fit. Preference heterogeneity was tested using a latent class model. The HK value set yielded a utility score of -0.870 for the worst health state (i.e., all dimensions at level 5), with physical health dimension contributing the largest decrement (-0.675), followed by dimensions well-being (-0.234) and activity (-0.218). The coefficient for the second level of the “activity” and “well-being” dimensions showed no statistically different from the reference level. For the dimensions of “choice, control, and autonomy” and “hope,” the coefficients for the second and third levels were identical. Sensitivity and preference heterogeneity analyses confirmed the overall stability of the value set. This study presents the first Asian value set for the ReQoL-UI, enabling quality-adjusted life years calculations to support cost-utility analyses of mental health programs and interventions in HK.