Predicting EQ-5D Index Scores from the PROMIS-29 Profile for the United Kingdom, France, and Germany

Abstract

Background: EQ-5D health utility (HU) scores are commonly used in health economics to compute quality-adjusted life years (QALYs). EQ-5D scores, which are country-specific, can be derived directly or by mapping from self-reported health-related quality of life (HRQoL) scales such as the PROMIS-29 profile. The PROMIS-29 from the Patient Reported Outcome Measures Information System is a comprehensive assessment of self-reported health with excellent psychometric properties. We sought to find optimal models for predicting EQ-5D scores from the PROMIS-29 in the United Kingdom, France, and Germany and compared the prediction performances with that of a US model.Methods: We collected EQ-5D-5L and PROMIS-29 profiles and three samples representative of the general populations in the UK (n=1,509), France (n=1,501), and Germany (n=1,502). We used stepwise regression with backward selection to find the best models to predict the EQ-5D score from all seven PROMIS-29 domains. We investigated the agreement between the observed and predicted EQ-5D scores in all three countries using various indices for the prediction performance, including Bland-Altman plots to examine the performance along the HU continuum.Results:The EQ-5D index scores were best predicted in Germany (RMSEGER = 0.10, MAEGER = 0.06), followed by France (RMSEFR = 0.11, MAEFR = 0.08) and the UK (RMSEUK = 0.12, MAEUK = 0.09). The Bland-Altman plots show that the inclusion of higher-order effects reduced the underprediction of low HU scores.Conclusions: Our models provide a valid method to predict EQ-5D-5L index scores from the PROMIS-29 for the UK, France, and Germany.