Adherence and Persistence with Glaucoma Therapy: Brimonidine/Timolol versus Dorzolamide/Timolol and Various Two-Bottle Combinations

Purpose: Patients with glaucoma often require multiple topical medications to reach target intraocular pressure. This database analysis examined persistence and adherence in patients’ prescribed fixed-combination brimonidine/ timolol, fixed-combination dorzolamide/timolol, or various commonly used two-bottle combinations. Participants: Glaucoma patients (ICD-9 code: 365.xx; n=7883) from the Source Healthcare Analytics Source® Lx database with an index prescription for fixed-combination brimonidine/timolol, fixed-combination dorzolamide/timolol, or various commonly used two-bottle combinations during the 6-month qualifying period (January 2008–June 2008), but not the 12 months before, were included. Methods: In this retrospective prescription database analysis, adherence and persistence for fixedcombination brimonidine/timolol were compared to fixed-combination dorzolamide/timolol and various commonly used two-bottle combinations. The two-bottle arms were: β-blocker+brimonidine; β-blocker+carbonic anhydrase inhibitor; β-blocker+prostaglandin analogue; carbonic anhydrase inhibitor+brimonidine; carbonic anhydrase inhibitor+prostaglandin analogue; and prostaglandin analogue+brimonidine. Main outcome measures: Persistence for brimonidine/timolol was compared with each of the comparators using Kaplan-Meier survival analysis for 12 months after the index prescription. Adherence was assessed using the medication possession ratio. Results: Kaplan-Meier analyses found that a significantly greater proportion of patients remained on treatment with brimonidine/timolol (34.9%) compared with each of the other treatments (13.4%–20.8%; p<0.0001) at the end of the study period. In addition, the 12-month medication possession ratio was significantly higher for brimonidine/ timolol (42.7%) than for each of the two-bottle arms (23.3%–34.9%; p<0.0001 for all comparisons). The medication possession ratio for brimonidine/timolol was also slightly, but significantly, higher than that for dorzolamide/timolol (40.6%; p=0.0208). Conclusions: Persistence and adherence are higher with a fixed-combination single bottle of brimonidine/timolol than with fixed-combination dorzolamide/timolol and commonly used two-bottle combinations.