The weight-specific adolescent instrument for economic evaluation (WAItE): psychometric evaluation using a Rasch model approach

Valuing selected WAItE health states using the Time Trade-Off methodology: findings from an online interviewer-assisted remote survey

PURPOSE

The Weight-Specific Adolescent Instrument for Economic Evaluation (WAItE) is a physical weight-specific patient reported outcome measure for use in adolescence. The purpose of this study was to use the Time Trade-Off (TTO) methodology, administered using an online interviewer-assisted remote survey, to obtain utility values for several health states from the WAItE descriptive system from a sample of the UK adult general population.

METHODS

The adult sample was gathered using a market research company and a sample of local residents. All participants completed the same interviewer-assisted remote survey, which included rating WAItE states of varying impairment using the TTO.

RESULTS

42 adults completed the survey. Utility values were gathered for four health states, ranging from low impairment to the most severe health from the WAItE descriptive system (the Pits state). Consistent orderings of the WAItE health states were observed; the health state with the lowest level of impairment was valued highest and the Pits state was valued lowest. Several respondents (n = 7, 17%) considered the Pits state to be worse than death; however, the mean value of this health state was 0.23.

CONCLUSIONS

The utility value of the Pits state relative to death generated from this study will be used to anchor latent values for WAItE health states generated from a Discrete Choice Experiment onto the 0 = death, 1 = full health Quality Adjusted Life Year (QALY) scale as part of a valuation study for the WAItE in the UK population. This study also provides further evidence that interviewer-assisted digital studies are feasible for collecting TTO data.

Developing a preference-based measure for weight-specific health-related quality of life in adolescence: the WAItE UK valuation study protocol

INTRODUCTION

Adolescent obesity is a public health problem in the UK. The Weight-Specific Adolescent Instrument for Economic Evaluation (WAItE) has been developed as the first weight-specific health-related quality of life measure appropriate for economic evaluation, but currently cannot be used to generate quality-adjusted life years (QALYs), which are the basis of cost-utility analysis. Generic measures (such as the EQ-5D-Y or CHU-9D) may be insensitive to small but important health changes in overweight or obese adolescents. This study aims to generate a preference-based scoring algorithm for the WAItE.

METHODS AND ANALYSIS

A discrete choice experiment (DCE) will be administered to value health states described by the WAItE classification system. These health states will be presented to members of the adult general population of the UK via an online survey. A range of regression models will be used to produce the utility algorithm for the WAItE. The DCE-visual analogue scale and time trade-off (TTO) anchoring methods will be used anchor the value set on to the 0-1 QALY scale.

ETHICS AND DISSEMINATION

The Newcastle University Medical School Ethics Committee approved the study (references 4772/2020 (DCE) and 9978/2020 (TTO)). The developed algorithm can be applied to future economic evaluations of weight management interventions and treatments for adolescents.

Implementing a weight-specific quality-of-life tool for young people in primary health care: a qualitative study

Background

Obesity is thought to be one of the most serious global public health challenges of the 21st century. The primary care setting is important in terms of the diagnosis, education, and management of obesity in children and young people. This study explored the views of primary care clinicians on the implementation of a quality-of-life (QoL) tool to help young people and their families identify the impact of weight on QoL.

Aim

To assess the acceptability and feasibility of implementing the Weight-specific Adolescent Instrument for Economic-evaluation (WAItE) QoL tool for young people aged 11–18 years in primary care.

Design & setting

Qualitative study in Northern England, UK

Method

One-to-one, semi-structured interviews were conducted with a purposive sample of primary healthcare clinicians working in practices located in areas of varying deprivation in Northern England, UK. Interview transcripts were coded and analysed using framework analysis in NVivo (version 10).

Results

Participants (n = 16 GPs; n = 4 practice nurses) found the WAItE tool acceptable for them and their patients, and believed it was feasible for use in routine clinical practice. It was important to primary care clinicians that the tool would provide an overall QoL score that would be easy for GPs and nurses to interpret, to help them identify patients most in need of specialist help.

Conclusion

This study has developed a platform for further research around QoL in young people who are overweight and obese. A future feasibility study will focus on implementing the tool in a small number of primary healthcare practices.