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A. L. Robin, D. Covert, G. D. Novack, R. S. Crockett, T. S. Marcic; A Comparison of Adherence to Glaucoma Medical Therapy for Patients on One Medication Compared to Two Different Medications Using a Computerized Medications Event Monitoring System (MEMS) Device. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5574.
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The importance of maintaining constant lowered intraocular pressure (IOP) in glaucoma treatment is borne out by the AGIS study. Thus, treatment adherence to ocular hypotensive therapy is key in preventing glaucomatous visual field loss. However, data on time-stamped use of ocular hypotensive therapy is sparse, especially with today’s therapies. We evaluated the use of ocular hypotensive therapy in a population of patients in a private practice using MEMS devices.
Enrolled were 62 patients, half currently using prostaglandin (PG) monotherapy (1 Rx), and half currently using PGs and a second bottle of ocular hypotensive medication (2 Rx). All provided informed consent and were repeatedly told that their medication use was being monitored. Subjects were examined at 30 and 60 days, but no adherence feedback was provided.
At entry, the 2 Rx group had slightly more severe glaucoma than the 1 Rx group (visual fields, cup-disc ratio). Overall, adherence with prescribed PG doses in both groups was excellent. In the 1 Rx group, 97% of patients had 5 or less dosing errors (missed and exceeded daily doses). This was similar to the patient adherence with PG doses of 90% in the 2 Rx group. However, patient adherence with the second medication dropped to 73% of patients having 5 or less dosing errors. Overall, patient adherence in the 2 Rx group was 63%. The timing of those doses was also variable and far from ideal. More than one-quarter of the inter-dose intervals were more than 2 hours late, compared with less than 10% of the prostaglandin dosing. Theoretical coverage (percent of time within the nominal dosing interval) was 85.6 ± 12.6%, with 23% (7/31) of patients having less than 80% coverage. This compared with an average of 97% coverage for the prostaglandin. Most patients using b.i.d. or q.d. dosing (89%, 25/28) had a least one inter-dosing drug intervals for the second drug less than 10 hours (nominal b.i.d dosing is 12 hours). Approximately one-quarter of doses of ß-adrenoceptor antagonists dosing intervals were less than 10 hours.
Time-stamped adherence data is was very useful in determining patients’ behavior vis-à-vis dosing of ocular hypotensive medications. Even in a population in a private office who were aware of monitoring, adherence was an issue, particularly with patients using more than one bottle of glaucoma medications.
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