Factors associated with adherence to glaucoma pharmacotherapy in the primary care setting

Background: Primary open-angle glaucoma is a leading cause of irreversible blindness. Objectives: To identify factors associated with adherence to glaucoma pharmacotherapy in the primary care setting, focusing on physicians' role. Methods: Patients were recruited from primary care clinics and telephone-interviewed using a structured questionnaire that addressed patient-, medication-, environment- and physiciansrelated factors. Patients' data on pharmacy claims were retrieved to calculate the medication possession ratio for measuring adherence. Results: Seven hundred thirty-eight glaucoma patients were interviewed. The multivariate analysis identified eight variables that were associated independently with adherence. Barriers to adherence were found to be low income, believing that 'It makes no difference to my vision whether I take the drops or not' and relying on someone else for drop instillation (exp(B) = 1.91, P = 0.002; exp(B) = 2.61, P < 0.0001; exp(B) = 2.17, P = 0.001, respectively). Older age, having a glaucoma patient among close acquaintances, taking a higher number of drops per day, taking a prostaglandin drug and reporting that the ophthalmologist had discussed the importance of taking eye drops as prescribed, were found to promote adherence (exp(B) = 0.96, P < 0.0001; exp(B) = 0.54, P = 0.014; exp(B) = 0.81, P = 0.001; exp(B) = 0.37, P < 0.0001; exp(B) = 0.60, P = 0.034, respectively). No association was found between the patient's relationship with the family physician and adherence to glaucoma treatment. Conclusion: Adherence to glaucoma pharmacotherapy is associated with patient-related, medicationrelated, physician-related and environmental factors. Ophthalmologists have a significant role in promoting adherence. However, the potential role of family physicians is unfulfilled and unrecognized.