Surgery: consider before adding another medication?

February 15, 2005

New Orleans—Adding a third or fourth medication to a glaucoma patient's therapeutic regimen has many drawbacks but a few potentially positive aspects as well and should be considered on an individual patient basis, said Shan C. Lin, MD, assistant professor of clinical ophthalmology, University of California, San Francisco, and San Francisco General Hospital.

New Orleans-Adding a third or fourth medication to a glaucoma patient's therapeutic regimen has many drawbacks but a few potentially positive aspects as well and should be considered on an individual patient basis, said Shan C. Lin, MD, assistant professor of clinical ophthalmology, University of California, San Francisco, and San Francisco General Hospital.

"In the final analysis, when is enough, enough?" Dr. Lin asked during a glaucoma presentation at the American Academy of Ophthalmology annual meeting.

"The answer is different for each individual patient," he said. "It depends on severity, preference, and compliance. You may consider using trabeculoplasty a little bit earlier or as initial therapy, and you may want to consider surgery before adding that third or fourth medication."

On the negative side, reasons to avoid adding a third or fourth medication include poor efficacy, added side effects, poor compliance, poor surgical outcomes, and added cost to the patient, Dr. Lin said.

He cited a retrospective study in which 67 patients (Group A) received a third medication and 29 patients (Group B) received a fourth. Success was defined as an IOP reduction ≥20%, no further surgery, and no discontinuation of medication. After 6 months, 27% of Group A and 31% of Group B met that standard, while at 1 year, there was no difference between the groups, with both achieving a 14% efficacy rate.

In addition to this dismal rate of efficacy among patients taking multiple medications, the local and systemic side effects are also a drawback, Dr. Lin said.

"As you go down the list of medications that you use, you have a greater number of side effects as well as severity of side effects, all of which lead the patient to be poorly compliant," he added.

Compliance an issue In another study, poorer compliance correlated with greater frequency of drops and multiple glaucoma medications. Among patients receiving a once- or twice-daily dosage, 51% admitted missed doses. The number increased to 61% among patients receiving more than twice-daily dosages, and among those receiving multiple medications daily, 68% admitted missed doses.

"The number one reason for being noncompliant was forgetfulness, which is not too surprising given that most of our patients are elderly and they have to remember to take many systemic medications," Dr. Lin said.

He added that cost is another significant reason for noncompliance.

Trabeculectomy outcomes are also affected by patients' use of medications, according to study results.

"The success of trabeculectomies went down as the number of prior medications increased," Dr. Lin said.

Defining success as IOP < 22 mm Hg without medication, the study authors found that the success rate was 93% among patients taking minimal medication or no medication; 90% among those taking only a beta-blocker; 72% among those taking a beta-blocker and a miotic; and 54% among those taking a beta-blocker, a miotic, and a sympathomimetic.

Despite these findings, there might be valid reasons for adding a third or fourth medication, Dr. Lin said. Data from the Collaborative Initial Glaucoma Treatment Study, which compared the efficacy and safety of surgery versus medication in patients with newly diagnosed glaucoma, showed that the group that underwent surgery had a better pressure reduction than the group treated with medication.

"However, in the final analysis, both groups did about the same in terms of visual field change over the course of the study, suggesting that medication treatment was as effective as surgery," Dr. Lin said.

Further, data concerning adverse events showed that there was a higher rate of cataract surgery in the group that underwent glaucoma surgery. This group also had a higher reported rate of local side effects.