ESTIMATING A CHINESE EQ-5D-5L VALUE SET USING NONLINEAR MODELS

Purpose: The availability of the 5-level EQ-5D descriptive system (EQ-5D-5L) provides the opportunity of developing a new preference-based instrument for health technology assessment. The purpose of this study is to estimate an EQ-5D-5L value set for China using the health preferences of residents living in the urban areas of the country.

Method: The utility values of 86 EQ-5D-5L defined health states were elicited using the time trade-off (TTO) technique from a sample of urban residents (n=1,271) recruited from 5 Chinese cities. In computer-assisted personal interviews, participants each completed 10 TTO tasks. Both the 20-parameter additive linear and the 8-and 9-parameter multiplicative nonlinear regression models were evaluated for their performance in describing the relationship between TTO values and health-state characteristics through cross-validation. Final values were generated using the best performed model and were rescaled to remove the effect of the model intercept on predicted values.

Result: The 8- and 9-parameter multiplicative models unanimously outperformed the 20-parameter additive model using a random or fixed intercept in predicting values for out-of-sample health states in the cross-validation analysis and their coefficients were estimated with lower standard errors. The prediction accuracy of the two multiplicative models measured by mean absolute error and intraclass correlation coefficient was very similar, thus favoring the more parsimonious model.

Conclusion: The 8-parameter multiplicative nonlinear model performed best in the study and therefore was used to generate the EQ-5D-5L value set for China. We recommend using rescaled values whereby 1.0 represents the value of full health in economic evaluation of health technologies in China whenever EQ-5D-5L data is available.