Low-Income Glaucoma Patients Less Likely to Use Eye Drops

SAN FRANCISCO, California — Glaucoma patients with low income and those with more severe disease are significantly less likely to take their topical medications, according to 2 new studies from the University of Toronto, Toronto, Ontario, Canada, and Stanford University, Stanford, California.

"Patients with low income were twice as likely as those with average or above average income to be nonadherent to their medication therapy in our research. That's quite significant," lead investigator Victoria Leung said of the research presented here at the American Glaucoma Society (AGS) 23rd Annual Meeting.

In another study of 126 patients treated at a county hospital in San Francisco, those who had severe glaucoma were more likely to be compliant than those with mild or moderate disease, lead investigator Cindy Ung from Stanford University School of Medicine, Stanford, California, told Medscape Medical News.

"Although we couldn't establish the reasons why patients with severe disease were more compliant, we inferred that these patients had more symptoms — and so were more likely to use their medications," Ung said.

Yet experts at the meeting said that this conclusion may be too far-reaching. Patients with more severe glaucoma may also have been in treatment for a longer time, and have more understanding of their disease, according to Joel Schuman, MD, chair of the department of ophthalmology at the University of Pittsburgh, Pittsburgh, Pennsylvania. "The researchers' results could be interpreted in several different ways," Dr. Schuman told Medscape Medical News.

In the Stanford study, patients completed an oral questionnaire to assess their knowledge of glaucoma. The patients' use of medications was analyzed with pharmacy refill data and was measured retrospectively over the 18 months prior to study entry.

The researchers' findings revealed that those with mild or moderate glaucoma were more likely to be nonadherent than those with severe disease (odds ratio 1.54; 95% confidence interval, 1.03 - 2.31; P = .04).

"We were surprised by the results because we reasoned that people with more severe disease would be more likely to be nonadherent because their disease may have progressed because of not being compliant with medication therapy," Ung said.

That's a little higher than I would expect, but there is a real problem with nonadherence in glaucoma patients.

In the University of Toronto study, 61 patients completed a questionnaire about socioeconomic issues such as income status and whether or not their basic needs for food, shelter, and transportation were met on a monthly basis. The researchers used pharmacy records over 1 year to assess medication compliance.

In Canada, people aged over 65 years have insurance coverage for their medications, but even those with low income in this age bracket were less likely to be compliant, Leung said. Those who reported not having basic needs met were also less likely to refill and take their medications, she noted.

The Canadian researchers found that 54% of the glaucoma patients in their study were noncompliant.

"That's a little higher than I would expect, but there is a real problem with nonadherence in glaucoma patients who take topical medication drops," Dr. Schuman said.

It's crucial to research the question of how to improve compliance, but, so far, most interventions tested in studies have shown limited efficacy, Dr. Schuman noted.

"We know adherence is lousy in glaucoma patients, but the question is, how do we make it better?" Dr. Schuman said.

He acknowledged that glaucoma patients often see the task of taking their medications as inconvenient, particularly if they are on several different medications or have to take drops more than once a day.

"Interventions such as having the patients fill out a medication sheet each day and timers to remind people to take their glaucoma medicines have all been tried," Dr. Schuman said. "But glaucoma still remains a disease where noncompliance is a problem."

The investigators for both studies and Dr. Schuman have reported no relevant financial relationships.

American Glaucoma Society (AGS) 23rd Annual Meeting: Abstracts 86 and 99. Presented March 2, 2013.