Challenges Associated with Estimating Utility in Wet Age-Related Macular Degeneration: A Novel Regression Analysis to Capture the Bilateral Nature of the Disease

Abstract

IntroductionThe estimation of utility values for the economic evaluation of therapies for wet age-related macular degeneration (AMD) is a particular challenge. Previous economic models in wet AMD have been criticized for failing to capture the bilateral nature of wet AMD by modelling visual acuity (VA) and utility values associated with the better-seeing eye only.MethodsHere we present a de novo regression analysis using generalized estimating equations (GEE) applied to a previous dataset of time trade-off (TTO)-derived utility values from a sample of the UK population that wore contact lenses to simulate visual deterioration in wet AMD. This analysis allows utility values to be estimated as a function of VA in both the better-seeing eye (BSE) and worse-seeing eye (WSE).ResultsVAs in both the BSE and WSE were found to be statistically significant (p < 0.05) when regressed separately. When included without an interaction term, only the coefficient for VA in the BSE was significant (p = 0.04), but when an interaction term between VA in the BSE and WSE was included, only the constant term (mean TTO utility value) was significant, potentially a result of the collinearity between the VA of the two eyes. The lack of both formal model fit statistics from the GEE approach and theoretical knowledge to support the superiority of one model over another make it difficult to select the best model.ConclusionLimitations of this analysis arise from the potential influence of collinearity between the VA of both eyes, and the use of contact lenses to reflect VA states to obtain the original dataset. Whilst further research is required to elicit more accurate utility values for wet AMD, this novel regression analysis provides a possible source of utility values to allow future economic models to capture the quality of life impact of changes in VA in both eyes.FundingNovartis Pharmaceuticals UK Limited.Electronic supplementary materialThe online version of this article (doi:10.1007/s12325-017-0620-x) contains supplementary material, which is available to authorized users.

Non-invasive testing for early detection of neovascular macular degeneration in unaffected second eyes of older adults: EDNA diagnostic accuracy study

“…Searches identified numerous potential sources. [93][94][95][96][97][98][99][100][101] An emphasis was placed on identifying values for visual acuity states based on the preferences of the UK general population. Given that there was some evidence to suggest that the EuroQol-5 Dimensions lack sensitivity to change in visual acuity, 102 directly elicited values for specific visual acuity states were considered where these had been elicited from a sample of the UK general population using an appropriate valuation technique.…”

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“…Health state utility data by VA status was identified from searches of the published literature. [14][15][16][17][18][19][20][21][22] , 23 For consistency with the NICE appraisals of ranibizumab and aflibercept, 24,25 we applied utilities reported by Czoski-Murray et al 22 based on UK general population time trade-off values for visual impairment states simulated using contact lenses. In line with the NICE appraisals, we used the published equation based on regression analysis of this data to assign health state utility weights in the model (Supplementary Table 3)…”

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“…Utility estimates were collected from a published study by Czoski-Murray et al using a time trade-off methodology (Table 2) (19). Only the treatment effect in the better-seeing eye was considered in this study; compared to the poorerseeing eye, it shows more notable correlation between utility values and vision (20).…”