Adherence with brimonidine in patients with glaucoma aware and not aware of electronic monitoring

Purpose: To assess the impact of open versus masked adherence monitoring on adherence with topical brimonidine using two different dosing schedules. Methods: Thirty-seven patients with glaucoma or ocular hypertension were enroled in a prospective, observational cohort study. Patients were randomly assigned to open or masked adherence monitoring and to brimonidine twice daily (BID) or three times daily (TID). Patients received conventional brimonidine eye drops with attached electronic monitoring devices for 4 weeks with weekly intraocular pressure measurements. Adherence calculations comprised dosing intervals, adherence rate and time covered. Subgroup analysis with anova included the factors masking, regimen, diagnosis and age. Results: Among 36 individually analysed patients, 12 (33%) had adherence rates above 75%, therein two (5%) > 90%. The mean adherence rate in 19 patients aware of adherence measurements was 70 +/- 17% for brimonidine BID and 65 +/- 14% for TID, not significantly different to the rates of 17 patients not informed about adherence measurements (77 +/- 6% BID, 62 +/- 9% TID, p = 0.24). On average, patients with brimonidine TID achieved significantly lower adherence rates (64 +/- 12%) than patients on BID (73 +/- 13%, p = 0.02). Still, patients on TID applied brimonidine more often (TID 1.9 +/- 0.3, BID 1.5 +/- 0.1 mean applications per day). The median coverage was 70% and showed no statistically significant difference between patients on BID and TID (p = 0.36). Conclusion: The study findings suggest that adherence measurements are not significantly altered by open adherence monitoring, which may simplify future adherence studies. Adherence with brimonidine eye drops was insufficient for most patients. These results demonstrate the necessity to develop new strategies to improve compliance in glaucoma therapy.