The cost-effectiveness of early screening and treatment for intermediate age-related macular degeneration (AMD)

Abstract

OBJECTIVE To determine whether grading for AMD during a diabetic retinopathy (DR) screening program would be cost-effective in Hong Kong.

METHODS A cost-effectiveness analysis based on a Markov model with six mutually exclusive health states was undertaken. It included grading for AMD and treatment with vitamin therapy for those with intermediate AMD. The outcome of the model was cost per quality-adjusted life year (QALY) gained. A public provider perspective was used. The measures of effectiveness were mostly taken from a local DR screening project except the transition probabilities and the utility values which were taken from overseas data. Costs were mainly taken from the Hospital Authority and salary scale 2009. The main assumptions and estimates were tested in sensitivity analyses. In this model, only subjects with non-sight threatening diabetic retinopathy were included and the possibility of disease regression and treatment benefit for those with advanced AMD were not considered. Both costs and benefits were discounted at 3%.

RESULTS The cost per QALY gained through grading for AMD at the time of DR screening and treatment with vitamins of appropriate cases was HK$47,397 after discounting. This would be considered highly cost-effective based on the World Health Organization’s threshold of willingness-to-pay (WTP) for a QALY, e.g. less than the annual per capita GDP HK$300,000. One way sensitivity analyses revealed that the cost per QALY was most sensitive to utility value, discount rate, progression rate from intermediate to advanced AMD, and compliance rate for the treatment. The cost-effectiveness acceptability curve showed that at a WTP for a QALY of $100,000 or more, this AMD screening programme has over 90% of probability of being cost-effective compared with no screening.

CONCLUSION Our cost-effectiveness analysis demonstrated that grading for AMD at the time of DR screening among diabetic patients would probably be cost-effective in a Hong Kong public hospital setting.