Adherence, persistence of glaucoma drug superior among prior latanoprost users

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Adherence and persistence among patients prescribed bimatoprost 0.03% or bimatoprost 0.01% was investigated using pharmacy claims data, and the results showed statistically significant differences favoring bimatoprost 0.01%.

By Cheryl Guttman Krader; Gail F. Schwartz, MD

Baltimore-Both adherence and persistence with glaucoma medication among prior latanoprost users are better among patients prescribed branded bimatoprost 0.01% (Lumigan 0.01%, Allergan) compared with bimatoprost 0.03%, according to results from a real-world study.

“Bimatoprost 0.01% (Lumigan 0.01%, Allergan) was developed to provide more efficient drug delivery and reduce hyperemia and discomfort as compared with its predecessor bimatoprost 0.03% (Lumigan 0.03%, Allergan), and a study comparing the two branded formulations showed that they had equivalent efficacy, but Lumigan 0.01% was associated with a significantly lower rate of adverse events,” said Gail F. Schwartz, MD, Glaucoma Consultants, Greater Baltimore Medical Center.

“Bimatoprost 0.03% is now available as a generic, and with the obvious needs for health care-cost containment, many providers or patients are seeking generics,” added Dr. Schwartz, who is also assistant professor, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, and University of Maryland School of Medicine, Baltimore.

Previous studies comparing the 0.03% and 0.01% bimatoprost formulations reported better adherence and persistence rates with the 0.01% branded product, which is important over the long-term because it should translate into more consistent IOP control. The current study corroborates the findings of the earlier studies in a larger patient population and by focusing on previous latanoprost users who may be less likely to experience tolerability issues relating to conjunctival hyperemia, she added.

Data for the retrospective, observational study was extracted from the Longitudinal Rx Database from IMS Health for a 3-year period beginning July 2010. It included 11,234 adults who filled at least one prescription for bimatoprost 0.01% (n = 7,780) or bimatoprost 0.03% (n = 3,454) between Jan. 1 and June 30, 2012 and had previously filled at least 1 prescription for generic or branded latanoprost. All of those patients were included in the persistence analysis, and 8,740 (bimatoprost 0.01% n = 6,035; bimatoprost 0.03% n = 2,705) were included in adherence and treatment status analyses based on having 12 months of continuous post-index pharmacy benefit eligibility.

Adherence to the index bimatoprost treatment was defined as the proportion of days covered (PDC) with study medication during the 365 days following the initial fill date. There were statistically significant differences favoring bimatoprost 0.01% over the 0.03% formulation for both mean adherence (PDC = 0.74 versus 0.68) and median adherence (PDC = 0.88 versus 0.75).

In addition, there were statistically significant differences favoring the bimatoprost 0.01% cohort over the 0.03% group for having a higher proportion of patients considered to have high adherence (PDC ≥0.80, 55.2% versus 48.7%) and a lower proportion of patients with low adherence (PDC ≤0.20 6.7% versus 10.8%).

“In an adjusted analysis, patients in the bimatoprost 0.01% cohort were 30% more likely than those in the bimatoprost 0.03% cohort to have high adherence and 41% less likely to have low adherence,” Dr. Schwartz said.

Analyses investigating proportions of patients remaining on their index prescription each month over the 12-month follow-up period showed that the rate was consistently higher in the bimatoprost 0.01% group than in the bimatoprost 0.03% group beginning by the third month. At month 12, there was a statistically significant difference between groups with 72.5% of patients who started on bimatoprost 0.01% remaining on that treatment compared with 53.6% of those in the bimatoprost 0.03% group.

Patients were considered persistent with their index medication if they refilled their prescription within 30 days after completing their existing days’ supply. At month 12, the proportion of patients showing persistence was significantly higher in the bimatoprost 0.01% cohort compared with the bimatoprost 0.03% group (52.7% versus 46.2%)

Subgroup analyses of adherence and persistence rates with patients categorized by age (<65 and ≥65) consistently demonstrated significant differences favoring bimatoprost 0.01%.

“Adherence with glaucoma therapy is a chronic challenge, and clinicians need to consider tolerability when making prescription decisions for their patients,” Dr. Schwartz said. “Several studies show that 40% of Americans prescribed glaucoma medications cannot consistently take one drop a day. Hyperemia and/or irritation are among the most common reasons for poor adherence and persistence.”

The study authors acknowledged the research has limitations, as it could not control for clinical imbalances between the bimatoprost 0.01% and bimatoprost 0.03% cohorts, could not account for any samples that may have been provided, and presumed that prescription refills were taken with perfect adherence, which may not have occurred.

Gail F. Schwartz, MD

E: schwartzgf@aol.com

Dr. Schwartz is a consultant/advisor to and receives lecture fees/grant support from Allergan.