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Stewart et al. have conducted an investigation expanding on the work conducted by the Ocular Hypertension Treatment Study (OHTS) evaluating the cost-effectiveness of treatment of people with ocular hypertension. The OHTS investigation published in 2006 found that treatment of people with IOP > 24 mmHg with additional risk factors (e.g., thinner corneas, higher IOP, older age, etc.) had an annual risk of progression to glaucoma in excess of 2% per year, and that this was cost-effective.
The use of risk calculators that consider the impact of all risk factors might be more informative in determining the costeffectiveness of treatment
Stewart and his colleagues simulated the natural history of ocular hypertension through glaucoma over five years employing practice patterns derived from OHTS. Specific unit costs used for medicati-ons, patient visits, and diagnostic and therapeutic procedures were obtained from Blue Cross/Blue Shield. Stewart confirmed the finding of the OHTS economic evaluation that treatment of all people with ocular hypertension was not cost-effective and found that treatment of older people (over the age of 76), higher IOP (greater than 25 mmHg), thinner corneas (less than 533 microns), and larger cup-to-disc ratios (greater than 0.6) was cost-effective. While Stewart and colleagues have identifi ed specific levels of risk factors that meet accepted standards of cost effectiveness, they have not considered potential interactions between the risk factors. For instance, suppose a person had a corneal thickness of 560 microns, and an IOP of 24 mmHg, and a cup-to-disc ratio of 0.4, this person might have an annual risk of greater than 2% depending on other risk factors such as visual field indices or age. Therefore, while the work by Stewart is important in identifying specific risk factors that might lead a physician or policy maker to determine that treatment is cost-effective, the use of risk calculators that consider the impact of all risk factors might be more informative in determining the cost-effectiveness of treatment.