Preferenze della popolazione italiana per gli stati di salute dell'EQ-5D

Objective: To estimate a value set for the calculation of Italian specific Quality-Adjusted-Life-Years (QALYs), based on preferences elicited on EQ-5D health states using the time trade-off (TTO) technique. Methods: the revised standard Measurement and Valuation of Health (MVH) protocol was followed. Twenty-five health states, divided into 3 groups and given to 450 subjects, were selected to obtain 300 observations per state. Subjects aged 18-75 years were recruited to be representative of the Italian general adult population for age, gender and geographical distribution. To improve efficiency, face-to-face interviews were conducted using the Computer Assisted Personal Interviewing approach. Several random effects regression models were tested to predict the full set of EQ-5D health states. Model selection was based on logical consistency of the estimates, sign and magnitude of the regression coefficients, goodness of fit and parsimony. Results: The most efficient model includes 10 main effect dummy variables for the EQ-5D domain levels and the D1 interaction term, which accounts for the number of dimensions at levels 2 or 3 beyond the first. This model has a R2=0.389 and an MAE=0.03, comparable to or better than models used in other Countries. The utility estimates after state 11111 range from 0.92 (21111) to -0.38 (33333). Italian utility estimates are higher than those estimated in the UK and Spain and used so far to assess QALYs and conduct cost-utility evaluations in Italy. Conclusion: A specific value set is now available to calculate QALYs for the conduction of health economic studies targeted at the Italian healthcare system.