The economic implications of glaucoma - A literature review

Glaucoma is a common ophthalmic condition, often associated with elevated intraocular pressure (IOP). It affects > 2 million people in the US, and the incidence is expected to exceed 3 million by 2020. However, relatively little is known about the cost of glaucoma compared with costs for other eye conditions. This comprehensive report reviews published literature on costs and cost effectiveness of treatments for glaucoma. Cost-of-illness studies in glaucoma focus on direct medical costs and generally exclude indirect costs. In general, increased costs are associated with increased severity or lack of control over IOP and the distribution of costs (e.g. medication vs procedures) varies with severity. A large number of studies have evaluated the cost of glaucoma medications, assessing the number of drops per bottle and associated cost per drop or per treatment dose. These studies have limited usefulness as they generally evaluate unit medication costs without including differential effectiveness or adverse effects associated with various therapies, and thus provide only one component of real-world costs for glaucoma. Broader comparative cost studies, mainly adopting a cost-minimisation approach, have evaluated the impact of differing treatments and management strategies on all types of medical care resource utilisation and associated costs, but a variety of metrics for success makes interpretation challenging. Studies have generally found beta(2)-adrenoceptor antagonists to be associated with greater healthcare costs than newer therapies. Among newer treatments such as prostaglandin analogues, no specific treatment has demonstrated a clear cost advantage over other treatments. A number of studies have modelled hypothetical cohorts of glaucoma patients through courses of therapy, projecting costs, outcomes and cost effectiveness. A majority of these cost-effectiveness models compare one of the newer prostaglandin analogues with older medications or with one another. Existing studies suggest that bimatoprost may be more cost effective than other agents. However, the effectiveness outcomes used in these studies vary, including achieving IOP thresholds, IOP-controlled days, percent reduction in IOP and QALYs. Methods used to determine costs also vary substantially between studies. Future evaluations of the burden of glaucoma need to consider the issues of comparability between, and generalisability of, study results. Differences in methods have created barriers to understanding the cost of glaucoma and comparing costs or cost effectiveness between studies. Furthermore, future studies should also consider direct costs of glaucoma generally not covered by health insurance as well as indirect costs of glaucoma. As new screening technologies for early detection of individuals at elevated risk of glaucoma are now in use, more complete estimates of the cost of glaucoma are critical for issues of resource allocation and health policy.