Quantifying Glaucoma Medication Adherence: The Relationship Between Self-Report, Electronic Monitoring, and Pharmacy Refill.

Abstract

Glaucoma medications reduce the risk of progressive visual field loss, but adherence to these medications is often poor. A better understanding of the appropriate metrics for quantifying glaucoma medication adherence is needed. We describe and compare different means of quantifying glaucoma medication adherence. Adults with glaucoma were enrolled in a prospective 2-site study. Participants completed a self-report instrument and received electronic medication monitors to use for ∼3 months. Pharmacy records were queried regarding requested refills over the monitoring period; medication possession ratio (MPR) was calculated. Of the 137 total participants, those who answered "Very confident" to the question, "How confident are you that you always remember to use your glaucoma medications?" and "No" to the question, "In the past 4 weeks, did you ever forget to take your medicine?" were more likely [odds ratio (OR) 2.78, 95% confidence interval (CI) 1.19-6.52] to take ≥80% of the prescribed doses according to electronic medication monitors. Mean MPR was 1.49, standard deviation (SD) 0.82, range 0.1-5.31. The proportion of participants taking greater than or equal to 80% of the prescribed doses according to the electronic monitors was 59% for participants with MPR <1.2 (n = 27), 63% for participants with MPR 1.2-1.8 (n = 27), and 88% for MPR >1.8 (n = 25). Asking about confidence may be a good method of screening for poor adherence for glaucoma medication. MPR may be an inadequate representation of glaucoma medication adherence.