How Common is Poor Adherence in Glaucoma?

Glaucoma is a leading cause of blindness. Eye care providers most commonly use ocular hypotensive medications (94% of the time ) when treating ocular hypertension and glaucoma patients. Treatment reduces the development or worsening of glaucoma by approximately 60%. However, adherence to prescribed glaucoma treatments is poor. A recent study showed that only 56% of patients used more than 75% of the expected doses. Studies using pharmacy records have shown that only 50% of glaucoma patients have a refill of their medication within 6 months of initial dosing.

What is the Cost of Poor Adherence?

The cost of poor adherence in medicine is staggering. Studies estimate that poor adherence costs over $100 billion annually, results in 125 000 excess deaths, and causes 20% of all hospitalizations.

The economic cost of poor adherence to glaucoma treatment and how it alters the risk of visual impairment is unclear. One study found that patients with “poor compliance with medical and surgical recommendations” had increased glaucomatous progression when compared to those with “good compliance” (50% vs 10%, odds ratio [OR], 8.6; P < .001). One caveat is that the authors did not delineate between medical and surgical compliance. In addition to increased risk of glaucomatous progression, noncompliant glaucoma patients may have a higher risk of visual impairment; waste unused medications; may require additional medications; and, if their disease worsens, need more eye care visits, additional diagnostic tests, and earlier surgery.

A minority view is that poorly adherent patients do not result in increased economic costs since they attain fewer refills of medications. This is unlikely, considering that medications accounted for a small fraction of the costs of glaucoma when compared to visual impairment costs, productivity losses, and nursing home placements—as well as the other expenses of worsening glaucoma. Also, the ocular hypertensive treatment study showed a small increased risk of cataract surgery in those treated with ocular hypotensive medications (7.6% vs 5.6% over 5 years, hazard ratio 1.56), but showed no significant change in foveal sensitivity, lens opacity classification system (LOCS) III score, or visual acuity. Even if a small increase in cataract occurs with ocular hypotensive medications, it is unlikely that the economic cost of excess cataract surgery and the rare surgical complications outweigh the benefits of treatment. Overall, studies examining the cost of poor adherence to glaucoma treatment and its effect on visual impairment and blindness are needed.

What is the Cost of Poor Adherence?

The cost of poor adherence in medicine is staggering. Studies estimate that poor adherence costs over $100 billion annually, results in 125 000 excess deaths, and causes 20% of all hospitalizations.

The economic cost of poor adherence to glaucoma treatment and how it alters the risk of visual impairment is unclear. One study found that patients with “poor compliance with medical and surgical recommendations” had increased glaucomatous progression when compared to those with “good compliance” (50% vs 10%, odds ratio [OR], 8.6; P < .001). One caveat is that the authors did not delineate between medical and surgical compliance. In addition to increased risk of glaucomatous progression, noncompliant glaucoma patients may have a higher risk of visual impairment; waste unused medications; may require additional medications; and, if their disease worsens, need more eye care visits, additional diagnostic tests, and earlier surgery.

A minority view is that poorly adherent patients do not result in increased economic costs since they attain fewer refills of medications. This is unlikely, considering that medications accounted for a small fraction of the costs of glaucoma when compared to visual impairment costs, productivity losses, and nursing home placements—as well as the other expenses of worsening glaucoma. Also, the ocular hypertensive treatment study showed a small increased risk of cataract surgery in those treated with ocular hypotensive medications (7.6% vs 5.6% over 5 years, hazard ratio 1.56), but showed no significant change in foveal sensitivity, lens opacity classification system (LOCS) III score, or visual acuity. Even if a small increase in cataract occurs with ocular hypotensive medications, it is unlikely that the economic cost of excess cataract surgery and the rare surgical complications outweigh the benefits of treatment. Overall, studies examining the cost of poor adherence to glaucoma treatment and its effect on visual impairment and blindness are needed.

How Do We Determine Adherence?

Glaucoma adherence is difficult to measure. Patients routinely overstate their level of adherence as compared with objective measures. Intraocular pressure is a poor surrogate for adherence since patients commonly increase their adherence in the day prior to visiting their eye care provider. Observational methods (eg, trained observer witnessing the administration) are impractical and intrusive. Pharmacy records may be valid for measuring compliance of large groups, but can be inaccurate for individual patients and difficult to attain. Objective methods, such as electronic dose monitors, are the best method of measuring compliance, but they are available free of charge for only one eye drop medication; are cumbersome in a clinical setting; they have varying accuracy; patients may falsify use; and eye care providers do not have an incentive to use them. Clinicians can purchase the medication event monitoring system or the MEMS cap (MEMS 6 SmartCap; Aardex, Union City, California, USA), which uses a bottle-within-a-bottle design to objectively measure compliance. This method is unlike the clinical setting since it requires extra steps including unscrewing the MEMS cap, removing the eye drop bottle, replacing the bottle in the MEMS cap container, and replacing the MEMS cap. Overall, an accurate, unobtrusive, objective method of determining and monitoring adherence is still needed.