Potential Impact of EQ-5D-5L Mapping Function Recently Recommended by the National Institute for Health and Care Excellence on Utility Values and Decision Making

Objectives In the absence of an accepted local EQ-5D-5L tariff, the National Institute for Health and Care Excellence (NICE) requires EQ-5D-5L responses to be mapped to the long-standing EQ-5D-3L UK value set. Their 2022 Manual recommends using the mapping function recently developed by the NICE Decision Support Unit (DSU), instead of the van Hout Crosswalk that was previously endorsed. Our aim was to compare utility values derived using these 2 mapping methods and assess the potential impact on decision making. Methods For all 3125 unique EQ-5D-5L health states, utility values for both mapping functions were obtained and compared using numerical analysis and data visualization. Simulations in synthetic patient populations were conducted to evaluate the potential impact of the mapping functions on utility values derived from EQ-5D-5L clinical trial data. Results For 1898 (61%) health states spread across the severity spectrum, the DSU mapping function generates a higher utility value than the van Hout Crosswalk. The mean difference was 0.062 (±0.139 SD), ranging from +0.619 to −0.198 for individual health states. The simulations suggest that mean utility values estimated with the DSU mapping function may lie higher than those obtained with the van Hout Crosswalk. Conclusions Not only the choice of EQ-5D instrument, but also the mapping approach can have an impact on utility values. The DSU mapping function may shift UK utility values further upward, potentially affecting NICE decision making. The use of various combinations of instruments, mapping functions, and tariffs may soon make it challenging to bring together historical 3L evidence and a growing body of 5L-based evidence.