Several years ago, when a senior official at the FDA was asked why there was such a difference in getting licensing for glaucoma medicines compared to glaucoma devices, the answer, slightly in jest, was, “The device has only got to show it makes a hole.” Times have changed. Medicine, including surgery and new surgical techniques, is increasingly being subjected to economic scrutiny to justify the introduction of novel technology and procedures. What may we soon have to do to justify new surgical devices and techniques?
HEALTH ECONOMICS
Health economics relates to the issue of how health care resources should be allocated in order to maximize efficiency. It attempts to attribute numerical values to the benefit accrued by both the individual and society as a result of the use of resources—in this case, a surgical treatment for glaucoma. This number is then compared to the value of the next best or existing alternative treatment option. By then comparing the changes in benefit to the changes in cost of the new treatment, the analyst has a solid numerical foundation on which to base assumptions about the efficiency of the new treatment relative to current practice. He or she can then make better-informed decisions on whether or not to fund the procedure and under what circumstances.
FACTORS DETERMINING A SURGICAL COST-EFFECTIVE ANALYSIS
When establishing the cost-effectiveness of a new surgical procedure, the analyst must take a variety of factors into account. Each stage of a potential treatment requires a cost analysis in order to comprehensively compare the changes in cost associated with the new surgical therapy relative to existing practice (Figure 1).
The utility (a measure of relative satisfaction) for the individual and society must then be analyzed in order to determine any incremental benefit of the new modality. For the utility to be compared with best practice, a generic unit of measurement is required. The quality-adjusted life year (QALY) is the most utilized unit of measurement in cost-effectiveness analysis. It is derived from the number of years and the quality of life that would be added by the intervention.
COMPARISON OF NEW AND EXISTING SURGICAL PROCEDURES
The factors analyzed may include and range from comfort and mobility to the cost of time spent in convalescence, number of follow-up visits, side effect profiles, success rates of the technique, and the additional cost of the technique itself. Many of these factors are usually calculated from peer-reviewed clinical trials. It is worth noting that there have been no recently conducted clinical trials of glaucoma surgical procedures in which cost-effectiveness has been a measured outcome.1
Modelling treatment decisions in glaucoma allows the input of data. The information is drawn from systematic reviews of the literature, where outcome measures such as success rates and complications have been reported. Various modelling strategies have been constructed and validated for glaucoma treatment.2
Once cost and utility analyses have been completed, the cost per QALY can be established. Sensitivity analysis can then be performed to see how sensitive the cost per QALY is to variations in assumed parameters (utility, costs, surgical success rate, etc.). There have been no explicit guidelines on what is acceptable as a cost per QALY, but a λ20,000 to λ30,000 threshold (roughly, $32,000-$48,000 USD) is generally accepted in the United Kingdom for approval of use in the Health Service.
A HEALTH-ECONOMIC ARGUMENT FOR A NEW SURGICAL PROCEDURE
When constructing a model, it is important to consider the pertinent outcome measures of glaucoma surgical procedures. These should be discussed with a health economist accustomed to building relevant models. The models are often complicated and are outside the scope of this article. During the discussion, all potential outcomes related to the cost of treatment and the cost to the patient (from side effects to a loss of vision) should be included. Without this information, the true cost-effectiveness cannot be calculated.
Modelling is an accepted process for building a costeffectiveness argument. Well-constructed, high-quality clinical trials of new surgical treatments are required to generate data for an economic model to calculate costeffectiveness. Information about the effectiveness of the new procedure (for example, the ability to maintain IOP at low levels recognized to prevent further visual loss4) will then be available. A new technique that has not undergone such a trial is unlikely to be accepted in the longer term by governing bodies. In the United Kingdom, glaucoma treatments have been carefully assessed in such a way by the National Institute for Clinical Excellence, and treatment guidelines have been proposed.5 Detailed cost-effective analyses have been conducted as part of this report for all available treatments. It is likely that similar evaluations will increasingly be used in the United States and around the world.
Using these models, the costs of contemporary medical treatment can be calculated, and different groups have carried out this exercise.7,8 The long-term costs of medical therapy are significant, especially if lower IOP targets associated with lower rates of glaucomatous progression are desired endpoints. Advanced glaucoma can cost twice as much to manage, due in part to an increased number of medications, visits, and tests. If the surgery is very costly with a high rate of complications or failure in the short term, however, then the economic savings rapidly disappear. A contrasting future scenario is a 10-minute operation using topical anesthesia and a more effective antimetabolite. If this intervention ensured a long-term IOP of 10 mm Hg, had a rate of complications lower than 1%, and produced minimal scarring, then the economic advantages would be clear.
Figure 2 is a simplified model comparing the costeffectiveness of the current standard of care for moderate open-angle glaucoma and the potential cost of a modified trabeculectomy where the success rate is close to 100% and the complication rates are 0%. Clearly, with current techniques, this is not achievable. For example, treating a cataract directly resulting from trabeculectomy must be considered in the total cost of the trabeculectomy. If the new treatment were less effective, then the cost would be far greater. For example, failure 2.5 years after trabeculectomy could add $4,200 for treatment with a prostaglandin analogue, $6,060 for an average of three extra follow-up visits per year, and $1,465 for cataract surgery (total = $11,725) over the 22.5-year follow-up period. This is a simplistic scenario with associated quality-of-life implications and other costs related to the patient's care likely to increase the overall cost.
Involving a health economist in analyzing the costeffectiveness of a new treatment allows physicians to make informed decisions about its potential long-term benefits for their patients.
Supported by the NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology in London.
Trishal Boodhna, MSc, is a health economist at Moorfields Eye Hospital in London.
Jonathan Clarke, MD, FRCOphth, is a consultant ophthalmologist at Moorfields Eye Hospital in London. Dr. Clarke may be reached at +44 20 7566 2087; jonathanclarke@doctors.org.uk.
Peng Tee Khaw, PhD, FRCS, FRCP, FRCOphth, FRCPath, CBiol FSB, FARVO, FMedSci, is the director of the NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London.
