Abstract
Purpose: :
Cost utility analysis of anti-VEGF therapy for age-related macular degeneration (AMD) has hitherto used health economic models based solely on visual acuity. Yet, there is evidence that contrast sensitivity may be better related to a person’s health-related quality of life (HRQoL) in AMD (Bansback et al. Qual Life Res 2006). The purpose of this study is to investigate the impact of using contrast sensitivity instead of visual acuity in health economic models of AMD. The consequences for quality-adjusted life year (QALY) gains and cost effectiveness of anti-VEGF therapy is described.
Methods: :
Using outcomes from the Avastin (bevacizumab) for choroidal neovascularisation in age-related macular degeneration (ABC) trial, two Markov models - one for contrast sensitivity and one for visual acuity - were constructed to predict transitions between disease states. Each state was associated with a health utility and cost consistent with the UK government perspective. A cohort of 100 patients was run through each model. QALY gains and incremental cost effectiveness ratios (ICERs) over a 5 year time horizon were calculated for the treatment group (bevacizumab) against the comparator (PDT, pegaptanib and no treatment). One-way and probabilistic sensitivity analyses were conducted.
Results: :
Bevacizumab was less costly and more effective than the comparator using either visual acuity or contrast sensitivity as an outcome. However, the model based around contrast sensitivity generated a higher incremental QALY gain than the model based around visual acuity, leading to a more favorable ICER. In the base case, the incremental QALY gain was predicted to be 29% higher in the contrast sensitivity model (+0.075 QALYs) than the visual acuity model (+0.058 QALYs).
Conclusions: :
These results demonstrate that different conclusions can be drawn as to the cost effectiveness of anti-VEGF therapy in AMD using visual acuity or contrast sensitivity outcomes, particularly when making decisions close to the cost effectiveness threshold. Health economic models based on visual acuity outcomes alone may underestimate the cost effectiveness of anti-VEGF therapy for AMD.
Keywords: age-related macular degeneration • quality of life • contrast sensitivity