Public health impact of neovascular age-related macular degeneration treatments extrapolated from visual acuity

PURPOSE. To estimate the potential public health impact of treatment with new medications intended to preserve vision in patients with neovascular age-related macular degeneration (AMD). METHODS. A Markov model was used to simulate the natural history of AMD over the lifetime of patients with diagnosed neovascular AMD from clinical trials and epidemiologic surveys. It applied to a cohort of patients aged 75 years, with newly diagnosed neovascular AMD in one eye, whose visual acuity was 0.7 logMAR. Probabilities were calculated for the risk of AMD in the remaining eye and for premature mortality. Results of the model were expressed as the duration of low vision (worse eye VA > 1.0 and better eye VA > 0.7 logMAR) and blindness (bilateral VA > 1.0 logMAR). Health consequences of blindness and low vision were estimated for depression, hip fractures, institutionalization, and life expectancy. RESULTS. For AMD patients with a 50% probability of VA > 1.0 logMAR at 1 year, in one eye, the probability of lifetime bilateral blindness was > 47%. The patients would live approximately 7 years with monocular vision > 1.0 logMAR and an additional 4 years with bilateral blindness and a > 15% probability of depression due to AMD. Life expectancy was decreased by approximately 2 years, > 90/1000 patients would sustain a new hip fracture, and 1.5% of the patients would require institutional care for visual impairment due to AMD. To achieve a defined public health outcome (visual impairment and consequent comorbidity), it was necessary for the VA effectiveness of new treatments to increase in parallel with disease severity. CONCLUSIONS. Comorbidity related to visual impairment contributes significantly to the public health impact of AMD. Aggressive lesions need highly effective treatments. Models may be used to compare the public health impact of placebo-controlled clinical trial results.