Determinants of adherence to glaucoma medical therapy in a long-term patient population

Estimate patient adherence to glaucoma medications and identify potential determinants of nonadherence.

Descriptive study.

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.

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).

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.