PRM45 Utility Estimation for Visual Acuity Health States: An Original and Pragmatic Approach to Transpose Published Evidence Into a More Flexible Estimation

Abstract

The NICE reference case stipulates cost-utility analysis as the preferred form of economic evaluation, with health effects expressed in QALYs and health states valued using a validated choice-based method such as the time-trade-off (TTO). The evidence-base describing the impact of visual impairment (VI) on quality-of-life is very limited. To date, the Czoski-Murray et al. (2009) utility values for 4 visual health severity groups are considered the most plausible set of utility values for use in eye-disorder economic models. These utility values, originally elicited through simulating VI similar to that associated with wet age-related macular degeneration, were recently applied in other retinal disorders such as diabetic macular edema. The objective of our analysis was to refine the mapping of utilities onto visual acuity (VA). OLS regression models were built to estimate the relationship between mid-point VA of 4 visual health severity groups and mean TTO scores as described in the literature. Linear and non-linear approaches for utility estimation as a function of the number of VA letters were explored. The linear regression for utility estimation was found to be statistically significant. The beta-coefficient for mid-point VA was 0.0054 (p=0.030) and 0.2864 for the constant term (p=0.034). Linear regression estimates were used to predict the utility value for 6 pre-specified VA health states: VA1 (0.766); VA2 (0.671); VA3 (0.616); VA4 (0.562); VA5 (0.507); VA6 (0.382). Published evidence on utility values for deterministic visual health severity groups may not easily transpose to alternative vision health-states. Our analysis demonstrated an original approach for utility estimation allowing a more flexible and robust method to map previously elicited VA-associated utilities onto alternate VA health-states. This method allows wider applicability of VA-associated utility estimation in other eye disorders characterized by VA impairment such as vitreomacular traction and macular hole.