Examining the Disability Paradox and Health State Utility Valuation in Achondroplasia

OBJECTIVES: Achondroplasia is a rare genetic disorder leading to disproportionate short stature impacting quality of life. People with these inherited and long-term health conditions may adapt to their given health state ( ie,. The “disability paradox”). Our study aims to develop an achondroplasia specific value set for the EQ-5D-5L to determine whether existing EQ-5D-5L value sets are relevant for this population.

METHODS: This study conducted an online DCE with time trade off (DCE_TTO) elicitation to value health states of the EQ-5D-5L for people with achondroplasia in the US, UK and Brazil. Respondents were presented with 17 pairs of EQ-5D-5L health states with an associated duration, and asked to choose which they preferred. Sample characteristics and EQ-5D-5L/EQ-VAS were also collected and analysed descriptively. A conditional logistic framework was applied to analyse DCE_TTO responses to generate a achondroplasia value set. The existing US EQ-5D-5L & the generated achondroplasia value set were applied to all 3125 combinations of the EQ-5D-5L and the utility difference compared.

RESULTS: A total of n=123 people with achondroplasia were included in the final sample following quality checks. The average age was 34.7 (SD 9.3) years and gender split was 51.2% male and 48.8% female. The average overall EQ-5D-5L score for the achondroplasia patients was 0.60 (SD 0.33), with an average EQ-VAS score of 70.3 (SD 18.7). The average utility difference between the US EQ-5D-5L & achondroplasia value set when applied to all 3125 EQ5D health states totaled 0.06. Additionally, the achondroplasia value set resulted in a higher utility than the US EQ-5D-5L value set in 67% vs 33% of health states.

CONCLUSIONS: Our findings indicated the presence of a disability paradox among people with achondroplasia, who reported higher health states, suggesting the impact of achondroplasia may be underestimated if compared to the existing US published general population value sets for the EQ-5D-5L.