First-year treatment patterns among new initiators of topical prostaglandin analogs

Objective: To evaluate treatment patterns and costs among new initiators of topical prostaglandin analogs in a managed-care population. Research design and methods: Annual costs were modeled using multiple inputs. A retrospective cohort design was used to identify treatment patterns for pharmacotherapy. The study population was identified from pharmacy claims for patients who met study inclusion criteria (patients initiating prostaglandin analog monotherapy). Published studies were used to estimate visit-related resource use and costs were obtained from published and standard sources. Results: In the cohort analysis, a total of 12 202 patients met study criteria: 2275 received bimatoprost, 7347 received latanoprost and 2580 received travoprost (1808 used the original formulation and 772 used the newer preservative formulation). Of patients meeting study criteria, 50% stopped all glaucoma therapy, 6% switched from their initial prostaglandin therapy, and the remaining 44% stayed on their initial prostaglandin for 1 year. Of patients remaining on prostaglandin analog monotherapy for 1 year, 22.7% of bimatoprost patients, 19.8% of latanoprost patients and 17.9% of travoprost patients (19.7% for the original formulation and 13.7% for the new formulation) required adjunctive therapy. Of those requiring adjunctive therapy, the median number of days until starting adjunctive therapy was 53 days for bimatoprost patients, 63 days for latanoprost patients and 83 days for travoprost patients (70.5 days for the original formulation and 109 days for the new formulation). The resources used at each visit were estimated at $424 for an initial visit and $70 for follow-up visits. Estimated first-year costs were $1294, $1199, and $1186 for patients initiating therapy with bimatoprost, latanoprost, and travoprost, respectively. Estimated travoprost costs were higher for the original formulation ($1203) than for the new formulation ($1160). Sensitivity analyses suggested that the cost estimates are robust to changes in costs and use of adjunctive therapies. Limitations: The use of a claims database without compliance data or clinical outcomes and the selection of new initiators of topical prostaglandin analogs limits the findings and does not allow projecting outcomes to all glaucoma patients. Conclusions: Use of adjunctive therapy in glaucoma is an important driver of glaucoma management costs. Based on the results of this study, it is possible that longer duration of monotherapy with prostaglandin analogs may be associated with lower annual costs. Further study should be conducted to validate these findings.