OBJECTIVES: Health state utilities are required to evaluate the cost-effectiveness of an intervention. Vignettes had been developed for aromatic amino acid decarboxylase (AADC) deficiency with input from caregivers, clinicians and other experts, which were then completed online by panel participants from the United Kingdom and France. The objective was to compare the results generated in those two countries.

METHODS: Representative samples of the general population in both countries were presented with a total of 5 health state vignettes: bedridden, head control, sitting unsupported, standing with assistance and walking with assistance. Health state utilities were elicited using time-trade off (TTO; 10-year time horizon) and the standard gamble (SG).

RESULTS: A total of 1598 participants completed the vignettes in the UK, 1001 in France, with only 37% incongruent responses in the UK and 27% in France. The mean health utilities (standard deviation) increased linearly as health states improve. TTO results for congruent UK responses were: bedridden 0.42 (+0.32); head control 0.48 (+0.32), sitting unsupported 0.58 (+0.31); standing with assistance 0.63 (+0.32); and walking with assistance 0.67 (+0.33). For France respective utilities were: bedridden 0.39 (+0.36); head control 0.48 (+0.36), sitting unsupported 0.53 (+0.37); standing with assistance 0.53 (+0.38); and walking with assistance 0.56 (+0.38). French respondents had the highest differences in terms of preference between the "bedridden" and "head control" health states (0.09); the UK respondents between “head control” and “sitting unaided” (0.1). Except for head control, the UK had higher utility values in each of the health states and the overall utility gain between the lowest and highest health state were higher in the UK compared to France (difference of 0.25 vs 0.17). Same patterns were observed for SG.

CONCLUSIONS: These country-specific health state utilities will be used for a cost-effectiveness model comparing a treatment for AADC deficiency to standard of care.