Determinants of Adherence to Glaucoma Medical Therapy in a Long-term Patient Population

Purpose: Estimate patient adherence to glaucoma medications and identify potential determinants of nonadherence. Design: Descriptive study. Methods: Two hundred patients with open angle glaucoma, ocular hypertension, or glaucoma suspects were interviewed regarding their glaucoma and its treatment and their charts were reviewed. Their ophthalmologist completed a brief assessment form. Drug utilization data were extracted from the provincial drug program database. Patients were defined as adherent if they filled at least 75% of the prescribed medication necessary for their treatment. Results: Data were available for 181 patients. About 62.9% were female and the mean age ( +/-SD) was 75.1 +/- 8.8 years. The mean number of years of glaucoma treatment was 10.7 +/- 9.3. Self-reported treatment adherence was 88.3%. On the basis of the drug database, the proportion of patients who were adherent to treatment was 71.8%. According to physicians, 74.6% of patients were adherent. Among patients considered by physicians as nonadherent, 71.1% (32/45) were adherent and among patients predicted as adherent, 72.1% (98/136) were adherent. There was no significant difference in adherence according to age, sex, education, and income. However, patients using fewer agents (P = 0.041) who were widowed (P = 0.041). or who lived alone (P = 0.042) were more adherent. Patients using prostaglandins analogs or beta-blockers were more adherent than those using carbonic anhydrase inhibitors (P < 0.05). Conclusions: Fewer medications, use of prostaglandin analogs or beta-blockers, living alone, and being widowed were significantly associated with adherence. Physicians were unable to significantly predict which patients are adherent.