Medication Compliance in Glaucoma Patients Varies

October 25, 2011 (Orlando, Florida) — A retrospective analysis of data from nearly 18,000 glaucoma patients in California has shown that although a third are medication-compliant, some 20% are not, and this pattern is evident from the beginning of medication use. Efforts to increase patient compliance with medication use should target specific patients.

"Our principal motivation for doing this study was to seek ways to improve patient care. The results of this study, as with others, point out that the more patients see their doctor, the better off they will be," said Jason Jones, PhD, from Southern California Kaiser Permanente Medical Group in Baldwin Park, who presented the results of the study here at the American Academy for Ophthalmology (AAO) 2011 Annual Meeting.

The investigators harnessed a Kaiser Permanente database of clinical data from a total of 3.4 million patients in California. The data from 1992 onward also included administrative data from 6000 physicians and 130 ophthalmologists.

Glaucoma was defined as both the presence of an International Classification of Diseases, Ninth Revision, code 365.X and a glaucoma prescription beginning within 90 days of patient examination. Adherence was evaluated as an adjusted medication possession ratio (MPR), defined as the days of medication access divided by the days in the system.

Scrutiny of the database identified 17,679 patients with incident glaucoma. Of these, 56% were older than 65 years, 51% were female, and 50% were white. Other conditions included hypertension (65%), diabetes (29%), and chronic pulmonary diseases (17%).

The overall mean and median rate of medication compliance were 52% and 57%, respectively. But this overall picture did not accurately reflect the real situation, the researchers believe. They found that the data were bimodal in terms of the MPR: 27% of the patients were poorly compliant, 31% were fairly complaint, and 31% were highly compliant.

This bimodal pattern was evident early on, after commencement of treatment and continuing for at least 5 years. A closer look at the data for 5556 highly compliant patients and 4732 poorly compliant patients revealed that low adherence was associated with younger age, higher comorbidity burden, higher hospital utilization, and less outpatient utilization. Examination of data on lipid-lowering agents revealed a similar picture. In addition, a chart review and patient interviews were done with 100 randomly selected patients. Although a small snapshot of the overall population, the information gained from these patients made the researchers confident that the claims data reflected patient experience.

"Glaucoma medication adherence in years 1 and 2 are the best predictors of adherence in subsequent years. Any interventions to increase compliance should consider the fact of the bimodal nature of compliance, and suggests specific targeting of patients," said Mr. Jones.

"This is a very nice study of a very vexing issue. The average patient takes about 8 different medications and sees a doctor at least once a month. That’s a big burden. It boils down to the fact that many patients don’t take all their medications. Just like flossing, medication adherence goes up just before and after a visit to the doctor," Brian Flowers, MD, from Ophthalmology Associates in Fort Worth, Texas, said in an interview with Medscape Medical News.

The study was funded by Allergen. Dr. Jones disclosed a relationship with Allergen; Dr. Flowers disclosed a relationship with Akon Laboratories, iScience, and Pfizer.

American Academy of Ophthalmology (AAO) 2011 Annual Meeting: Abstract #PA057. Presented on October 24, 2011.