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

INTRODUCTION: The 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. METHODS: Here 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). RESULTS: VAs 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. CONCLUSION: Limitations 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. FUNDING: Novartis Pharmaceuticals UK Limited.

The Cost-Effectiveness of Ranibizumab Treat and Extend Regimen Versus Aflibercept in the UK.

INTRODUCTION: Wet age-related macular degeneration (AMD) is a chronic eye condition that causes severe deterioration of vision and even blindness. Current wet AMD treatment in the UK involves the vascular endothelial growth factor inhibitors ranibizumab and aflibercept. Patients with wet AMD require frequent and long-term monitoring for treatment to be effective, contributing to a substantial resource burden at wet AMD centers. The European license for ranibizumab was recently updated with an individualized 'treat and extend' (T&E) regimen, comprising a structured monitoring and treatment protocol. This study evaluated the cost-effectiveness of ranibizumab T&E versus aflibercept within a UK setting. METHODS: An individual patient-level simulation model was developed utilizing treatment effects from a network meta-analysis of randomized controlled trials. The model was conducted from a UK National Health Service (NHS) perspective over a lifetime horizon and the base case utilized probabilistic sensitivity analysis to assess uncertainty in the model. Additional scenario analyses were conducted to assess the impact of changes to the model inputs. RESULTS: Ranibizumab T&E was found to be more effective and less costly than aflibercept, providing, on average, an additional 1.058 quality-adjusted life years (QALYs) and a cost-saving of £19,604 over a lifetime horizon. At list price, ranibizumab T&E was found to be cost-effective versus aflibercept in 100% of simulations at a willingness-to-pay threshold of £20,000 per QALY. The robustness of the results was tested in several scenario analyses; ranibizumab T&E was found to be more effective, and less costly, than aflibercept in the vast majority of cases. CONCLUSION: This evaluation suggests that treating patients with ranibizumab according to the T&E regimen could be a better use of NHS resources than aflibercept, and could, therefore, be considered as a first-line regimen for patients with wet AMD in the UK. FUNDING: Novartis Pharmaceuticals UK Limited.