PP93 The Impact Of Using Different EQ-5D Scoring Methods On Cost-Utility Outcomes: A Simulation Study

Introduction Patients’ EQ-5D health states are preferably valued using country-specific value sets. If value sets are not available, crosswalks may be used to estimate utility values. However, up until now the impact of using crosswalks instead of value sets on cost-utility outcomes remains unclear. Methods Trial-based cost-utility data were simulated for four conditions (depression, low back pain, osteoarthritis, and cancer), three levels of disease severity (mild, moderate, and severe), and three treatment effect sizes (small, medium, and large), resulting in 36 scenarios. For all scenarios, utility values were estimated using four scoring methods (EQ-5D-3L value set, EQ-5D-5L value set, 3L-to-5L crosswalk, and 5L-to-3L crosswalk) for three countries (the Netherlands, the United States, and Japan). Mean utility values, quality-adjusted life years (QALYs), incremental QALYs, and cost-utility outcomes (incremental cost-effectiveness ratios [ICER], probabilities of cost-effectiveness at willingness-to-pay [WTP] thresholds) were compared between value sets and crosswalks. Results Differences between value sets and crosswalks ranged from -0.33 to 0.13 for mean utility values, from -0.18 to 0.13 for QALYs, and from -0.01 to 0.08 for incremental QALYs. Because of the small differences in incremental QALYs, ICERs between scoring methods were considerably different. For small effect sizes, at a WTP of EUR 20,000/QALY gained, the largest difference in the probability of cost-effectiveness was found for moderate cancer between the 5L value set and 3L-to-5L crosswalk (difference 0.63) using Japanese valuations. For medium effect sizes, the largest difference was found for mild cancer between the 3L value set and the 5L-to-3L crosswalk (difference 0.06) using Japanese valuations. For large effect sizes, the largest difference was found for mild osteoarthritis between the 3L value set and 5L-to-3L crosswalk (difference 0.08) using Japanese valuations. Conclusions Our findings indicate that reimbursement decisions may change depending on the use of crosswalks. Crosswalks are justifiable in absence of country-specific value sets but should not be considered a sustainable alternative for value sets.