Factors Affecting Adherence to Topical Glaucoma Therapy: A Quantitative and Qualitative Pilot Study Analysis in Sydney, Australia

Abstract

To assess which factors in the lives and disease of patients with glaucoma affect their adherence to topical glaucoma therapy and the quantitative significance of this effect. To assess qualitatively the most influential barriers to adherence from the perspective of the patient. Multicenter, prospective, cross-sectional pilot study. A total of 145 patients, attending outpatient metropolitan glaucoma clinics in Sydney, Australia, who were prescribed topical glaucoma medications. A structured interview-based questionnaire was conducted with 145 individuals using glaucoma eye drops that had been prescribed at least 2 weeks previously. The questionnaire involved 2 novel questions on adherence, 29 questions on factors identified or postulated in the literature as affecting adherence for quantitative analysis, and 1 open-response question on patient-identified causes of nonadherence for qualitative analysis. This questionnaire represents the broadest coverage of factors hypothesized to affect adherence in a single study in the glaucoma medication adherence literature to date. Adherence rate, risk factors for poor adherence, and patient-identified barriers to adherence. In response to the question "How many days have you missed a drop in the last 2 weeks," 69.7% of patients reported total adherence. Four factors were significantly related to an increased likelihood of reporting having missed drops in the last 2 weeks. These were difficulty applying drops (odds ratio [OR], 2.35; 95% confidence interval [CI], 1.02-5.44; P < 0.05), a past or current diagnosis of depression (OR, 3.61; 95% CI, 1.53-8.52; P < 0.01), patient self-rating of own memory ≤ 7 of 10 (OR, 3.15; 95% CI, 1.36-7.30; P < 0.01), and self-reported motivation score ≤ 6 of 10 (OR, 10.94; 95% CI, 3.00-39.81; P < 0.01). Patient understanding of glaucoma, ethnicity, and socioeconomic status were among the 25 factors found not to have a statistically significant correlation with adherence. There is a significant proportion of patients taking their topical glaucoma medications less often than prescribed. Adherence to topical glaucoma therapies is negatively correlated to several factors: difficulty applying drops, a past or current diagnosis of depression, poor self-rating of own memory, and poor self-rating of own motivation. These may prove useful in designing interventions to improve adherence in these patients.