Generic latanoprost may improve patient adherence with lower costs vs. brand-name agents

Switching glaucoma patients to a generic from a brand-name medication may be helpful for racial minorities and those with high copays.

Issue: July 10, 2015

Switching from a brand-name prostaglandin analogue to generic latanoprost may improve patient adherence in the treatment of open-angle glaucoma, according to a study presented at the American Glaucoma Society annual meeting.

“It is well known that medication adherence is a major challenge for many patients,” Joshua D. Stein, MD, MS, said at the meeting, delivering study results that were published in Ophthalmology. “There are a number of reasons why patients struggle with adherence, one of which is medication costs.”

Prostaglandin analogues are the most commonly prescribed drug for the treatment of open-angle glaucoma because they are efficacious with once-daily dosing and have a relatively benign side effect profile, Stein said. However, they can cost patients more than $100 out of pocket per month. When generic latanoprost became commercially available in March 2011, it became a considerably cheaper option with the potential for saving patients more than $1,300 annually compared with brand-name prostaglandin analogues, he said.

Study design

Quantifying how cost plays a role in patient adherence to a glaucoma medication regimen has been difficult in other studies, Stein said. “Patients may not want to [cooperate]. Some feel embarrassed or ashamed to admit that medication cost is a factor that is limiting their ability to be adherent when they’re filling out research surveys or participating in focus groups,” he said.

The current study did not rely on patient self-report to assess adherence, as the data source was claims data from a large nationwide U.S. insurance company.

The study compared adherence rates of 8,427 patients with open-angle glaucoma, age 40 years or older, who were continuously enrolled in the health plan from September 2009 to December 2012. Patients had to have at least one prescription in the first 18 months for one of the brand-name agents: Xalatan (latanoprost, Pfizer), Travatan Z (travoprost, Alcon) or Lumigan (bimatoprost, Allergan).

The study quantified adherence during the 18 months before generic latanoprost was introduced and the 18 months after it became available.

There was little change in adherence for those who continued taking a brand-name prostaglandin analogue during both periods, while adherence rose in the subset of patients who switched to the generic product in the post-introductory period.

Variables associated with at least 25% improved adherence included pre-generic use of travoprost or bimatoprost exclusively (relative to Xalatan), use of generic latanoprost after its introduction (relative to any of the brand-name agents), higher copays in the pre-generic period, lower copays in the post-introductory period and black race.

Variables associated with a 25% or more reduction in adherence included use of a brand-name prostaglandin analogue throughout the entire study, higher monthly copays in the post-introductory period, lack of eye care provider visits and black race. Another interesting finding is among all of the patients studied, 7% stopped treatment altogether after generic latanoprost became available with no record of other glaucoma medicines or laser/incisional intraocular surgery being performed, Stein said.

In the study, black race was a variable found to be associated with improved and decreased adherence.

“Our finding that black patients had higher odds than white persons of demonstrating a drop in medication adherence is consistent with several prior studies,” Stein said. “Black persons tend to have more severe disease and a more complex medication regimen, which certainly can affect adherence.”

However, despite this known underlying tendency for blacks to be less adherent, the availability of generic latanoprost appears to help blacks more than whites improve their adherence.

Practical application

Stein recommended switching patients who struggle with adherence to generic medication when possible. “This can be particularly helpful in patients with high medication copays and racial minorities,” he said.

With regard to the subgroup of patients who stopped treatment after generic latanoprost became available, Stein said, “At a time when medications become available as generic, we as ophthalmologists need to be cognizant that this is a time when some of our patients may stop treatment altogether. To encourage patients to switch to generics, insurers may stop paying for the brand-name medication, or patients may need to follow up with their eye care provider to get a new prescription for the generic agent, and these barriers may lead some patients to simply stop treatment altogether.” – by Kristie L. Kahl

Reference:
Stein JD, et al. Ophthalmology. 2015;doi:10.1016/j.ophtha.2014.11.022.

For more information:
Joshua D. Stein, MD, MS, can be reached at University of Michigan, Kellogg Eye Center, 1000 Wall St., Ann Arbor, MI 48105; email: jdstein@med.umich.edu.

Disclosure: Stein reports no relevant financial disclosures.