Modeling the cost of POAG
Jonathan Crowston, Hugh Taylor
The downturn in the global economy has made health economic studies
into the cost of vision threatening diseases such as glaucoma even more
pertinent. Detailed economic analysis of glaucoma costs are generally
lacking, in particular studies that incorporate both direct and indirect
costs and those that estimate the cost of glaucoma to society as a whole.
The challenges associated with quantifying the economic impact of glaucoma
were outlined recently in this journal (IGR 9-4). Here we report on a recent
economic analysis performed by the Centre for Eye Research Australia in
conjunction with Access Economics that assessed the current and future costs
of POAG in Australia.1
A dynamic model was generated to estimate the economic impact of
POAG in Australia with the purpose of advising policy makers on the present
and future costs of this disease and assessing the potential impact of future
interventions such as changes in diagnosis rates and the availability of
new treatment modalities to delay vision loss in glaucoma.
The model was informed by an extensive literature review and based, where
possible, on data derived from population studies. These data informed the
estimation of various parameters including: risk factors for POAG, progression
rates, treatment efficacy, quality of life and the costs of co-morbidity
such as falls and depression
In 2005 it was estimated that the prevalence of POAG was around 210,000 with numbers expected to rise to around 380,000 by 2025 due largely to the increasing aging population. The associated rates of visual impairment are expected to double from 24,000 to around 50,000 by 2025. The annual health system costs, which included the cost of treating co-morbidities, were in excess of $350 million and when indirect costs were factored in, the total cost increased to $1.9 billion. Future costs in real dollar terms are expected to in crease to $790 million and $4.3 billion by 2025.
The advantage of developing such a dynamic model is that it additionally permits the investigator to rapidly perform comparisons of the cost-effectiveness of future interventions. In the Tunnel Vision Report,1 three potential scenarios were analyzed to assess their cost impact in relation to continuation of current practices.
These included:
- Reducing the proportion of people with undiagnosed glaucoma (from current 50% to 20 or 10%). The analysis suggested that increasing diagnosis rates, while cost-effective, would be relatively expensive at between $150,000 and $170,000 per DALY avoided.
- A change in treatment protocol, (here a change in first line treatment from topical medication to laser trabeculoplasty) is very cost efficient.
- Availability of a new therapy such as a neuroprotection drug that would delay progression by a further 50% over and above the reduction obtained by current treatments would be cost saving at a notional treatment cost of $1000 pa. New treatments with the same efficacy would become relatively expensive above $5000 pa (cost effectiveness ratios beyond $60,000 per DALY avoided).
Comparison of the cost effectiveness of various disease interventions provides a valuable tool for directing ongoing policy development and establishment of best practice guidelines. We hope that the Tunnel Vision report will stimulate further work in this area.
1Tunnel Vision: The economic impact of primary open-angle glaucoma � a dynamic economic model by the Centre of Eye Research Australia and Access Economics (Available at www.cera.org.au or to request a copy of the report please e-mail cera-info@unimelb.edu.au)
