Glaucoma treatment costs present economic ramifications

"A recent estimate of the incidence of primary open-angle glaucoma (POAG) is that 2.22 million individuals are affected, 0.5 million have angle-closure glaucoma, and a smaller number have secondary glaucoma. Overall, about 3 million people have some form of glaucoma," Dr. Quigley said.

The number of patients treated can be extrapolated from, for example, the Blue Mountain Eye Study, whose data can be interpreted to show that for every five patients treated, three have glaucoma and two have ocular hypertension. Based on a large database from an insurance provider, Dr. Quigley explained that physicians are treating patients with ocular hypertension and glaucoma in a ratio of about 1:1; an estimated 1.3 million patients with ocular hypertension are currently being treated in the United States. Approximately 2% of patients with ocular hypertension have progression to glaucoma annually.

"If the patients who are now receiving treatment were left untreated, considering that the rate of untreated glaucoma progression is about 8% annually and that about 4% of treated patients have progression of visual field loss annually, the average length of time from the development of visual field loss to death is about 13 years, and 18 years for those with ocular hypertension. These data indicate that all patients with ocular hypertension are not going to go blind in their lifetimes, although many will develop some field loss," Dr. Quigley pointed out. He is the A. Edward Maumenee Professor of Ophthalmology and director of the Glaucoma Service and the Dana Center for Preventive Ophthalmology at the Wilmer Eye Institute, Johns Hopkins University, Baltimore.

Assuming that 10% of patients with POAG develop unilateral blindness, which is at the high end of present estimates, the implication is that of the 322,000 individuals spared from progression to glaucoma, 10% of them, 32,200, were saved from unilateral blindness.

Economic analysis

Analyses of the cost of treating individuals with ocular hypertension or glaucoma usually use the wholesale price of prescription drugs. Patients who do not have insurance, however, pay full price for the drugs, as high as $837 annually for one prostaglandin analogue.

"Treatment of glaucoma in the United States is costing about $4 billion total for office visits and drugs. The treatment of 1.3 million patients with ocular hypertension costs $1 billion for eye drops at the retail price. Assuming that there is a constant proportion of 32,200 eyes saved from unilateral blindness over a period of 25 years, about 1,200 eyes each year, the cost of saving one eye from blindness is $800,000 at the present treatment costs. This amount, however, raises the public health question-what is the trade-off between a quality-adjusted life year saved and the amount spent?" Dr. Quigley said.

One analysis found that compared with other medical therapies, the amount is reasonable if the treated eyes are those of patients with ocular hypertension who are at great risk of blindness. A Scandinavian study reported that surgery was not cheaper than medical treatment because of the high rate of unsuccessful surgery or the subsequent need for eye drops and cataract surgery because of surgical failure or complications that lead to even greater costs.

Side effects of therapy can take a big toll in addition to the effects of topical therapy; for example, falls resulting from treatment with eye drops are greater among patients with glaucoma, and breaking a hip may lead to early death.

The development of cataracts, however, seems to have the biggest impact.