A comparison of United Kingdom and Spanish general population time trade-off values for EQ-5D health states.

Few studies have compared preference values for health states obtained in different countries. The present study compared Spanish and United Kingdom (UK) time trade-off values for EuroQol-5D health states. The same preference elicitation protocol was followed in both countries. Differences in values for 43 health states rated directly were analyzed using t tests, and regression coefficients generated by random effects modeling were compared by aggregating the 2 value sets and using dummy variables to analyze country effect by dimension and level of severity. For the milder health states, Spanish and UK value assignation was similar; for intermediate health states, Spanish values were both higher and lower than UK values, whereas for health states worse than death, UK values were generally higher than Spanish values. There were statistically significant differences (P < 0.01) in values for 34.9% of health states rated directly, and some preference reversals between countries. UK raters ascribed greater importance to dimensions of pain/discomfort and anxiety/depression, whereas Spanish raters placed more importance on functional dimensions of mobility and self-care. Further analysis is required to determine how these differences affect cost-effectiveness and cost-utility analyses.