OBJECTIVES: Approximately 7.4 million people in the USA have an intellectual disability (ID). This population experience some of the greatest health inequalities, losing 22-26 life years compared to the general population. Whilst there are clear health inequalities, this population is often excluded from research and they have difficulty completing questionnaires such as the EQ-5D. A modified EQ-5D-3L was developed for adults who have mild to moderate ID.

METHODS: Qualitative cognitive think aloud interviews with carers of adult with ID were undertaken to explore key difficulties experienced with the EQ-5D. Results were incorporated with findings from a systematic review of adaptations to quality of life measures for this population. Alternative wording and structure of a modified EQ-5D-3L, with images, was developed through an iterative design process with focus groups and stakeholders. The performance of a modified EQ-5D-3L was examined using test-retest interviews with adults with ID where adapted, standard and proxy EQ-5D versions were completed.

RESULTS: Between September 2020 and June 2021, 64 participants from across England consented to participate. We found that a modified EQ-5D-3L is acceptable, reliable and valid. Four of five domains and three of five domains show stronger test-retest reliability than the standard EQ-5D-3L and proxy-completed versions, respectively. Over 85% of participants preferred completing the modified EQ-5D-3L compared to the standard EQ-5D-3L.

CONCLUSIONS: The modified EQ-5D-3L was well-accepted by participants, easier to administer and understand. Full statistical results will be reported. The EQ-5D-3L modified for adults who have ID will help facilitate measurement of their health-related quality of life and inclusion in research. Research is underway incorporating this modified version in economic evaluations.