Objective: To compare patient adherence and persistence with bimatoprost 0.01%, a new formulation that offers equivalent intraocular pressure-lowering efficacy to bimatoprost 0.03% and improved tolerability, with that of the original bimatoprost 0.03% formulation.
Methods: Pharmacy claims from a longitudinal database of prescription and medical claims for >115 million patients were analyzed. Patients with an initial (index) prescription for bimatoprost 0.01% or 0.03% between April and June 2011, and with no claim for ophthalmic prostaglandin or prostamide analogs during the preceding 18 months, were identified. Treatment adherence was expressed as the proportion of days covered (PDC) with study medication over the first 365 days after the index prescription. Treatment persistence over the first 12 months following the index prescription was assessed using Kaplan-Meier analyses, assuming a 30 day grace period for prescription refill. Treatment status (on/off study medication) was determined monthly for 12 months post-index.
Results: In total, 6150 patients were assessed for treatment adherence and 7660 for persistence. Adherence was significantly better with bimatoprost 0.01% than bimatoprost 0.03% (mean PDC 0.540 vs. 0.438; p < 0.001). Significantly more patients had high adherence (PDC > 0.80) with bimatoprost 0.01% than 0.03% (29.1% vs. 17.3%; p < 0.001). Persistence was also significantly better with bimatoprost 0.01%, with 29.5% (95% confidence interval [CI]: 28.3%, 30.8%) versus 18.3% (95% CI: 16.8%, 19.9%) of patients remaining on continuous treatment for 12 months (p < 0.001). At 12 months, significantly more patients were 'on treatment' (continuing/restarting treatment) with bimatoprost 0.01% than 0.03% (48.8% vs. 33.9%; p < 0.001). Sensitivity analyses demonstrated similar findings in cohorts of ocular hypotensive treatment-naïve and elderly (≥65 years) patients.
Conclusions: Bimatoprost 0.01% offers adherence and persistency advantages over bimatoprost 0.03% in patients requiring ocular hypotensive therapy. Study limitations included the observational design, lack of control for imbalances in patient characteristics, and assumption that prescription refill is synonymous with medication use.