Estimating health-related quality of life for adults with mild to moderate learning disabilities: An adaptation of the EQ-5D-3L

Objectives: In the UK, approximately 1.5 million people with learning disabilities face significant health disparities, living on average 20 years less than the general population. More research is needed in order to address these inequalities. Prior studies have indicated difficulty with the completion of the EQ-5D-3L among this demographic. This thesis critically addresses the underrepresentation of people with learning disabilities in health economics research by aiming to adapt the EQ-5D to better accommodate their needs. The objective is to facilitate their inclusion in health economics research, thereby ensuring that health resource allocation is more equitable and accurately reflects their health values.
Methods: Following a review of existing studies involving adults with learning disabilities, which developed/adapted quality of life measures, the wording, content and format of the EQ-5D were examined using interviews and focus groups with carers and supporters of adults with learning disabilities. Results were incorporated into an adapted EQ-5D-3L for adults with learning disabilities. A test-retest survey was undertaken to determine the reliability, acceptability and validity of the adapted version. A discrete choice experiment was designed for which identical choice sets using the standard EQ-5D-3L and the adapted version were completed by members of the general population. Mixed logit models were used to analyse the data. Comparisons of health state utility values were completed.
Results: The adapted EQ-5D-3L demonstrated improved acceptability and ease of completion among adults with learning disabilities, with most reporting consistent and reliable responses. Analysis of the DCE and visual analogue scale (VAS) responses from the general public revealed that the adapted measure typically results in lower and more variable health state utility values than the standard EQ-5D-3L, suggesting that the modifications impact valuation outcomes; however, these differences were not significant.
Discussion: The thesis recognises limitations such as sample representation and the effects of remote data collection during the pandemic, which may have influenced participant engagement and data quality. Future research directions include further validation with larger, more diverse samples. This work highlights the urgent need for methodological innovations that include the voices of people with learning disabilities in economic evaluations, aiming to improve health outcomes and ensure fair resource distribution.