First-year treatment costs among new initiators of topical prostaglandin analog identified from November 2007 through April 2008

Abstract

Objective:Ocular surface disease (OSD) is a common side effect of ophthalmic medications containing the preservative benzalkonium chloride (BAK). Little is known whether and how glaucoma treatment patterns and annual costs vary based on the presence of BAK. The objective of this analysis was to estimate first-year treatment costs among new initiators of topical prostaglandin analogs in a managed care population.Research design and methods:A model was developed to estimate first-year direct medical costs associated with glaucoma prescriptions and outpatient ophthalmic care. Patients were identified from a pharmacy claims database, covering more than 75 million individuals, if they initiated therapy with one of three prostaglandin analog products between November 1, 2007 and April 30, 2008. Patients needed to have at least 6 months of prior claims data in which there were no glaucoma therapy claims and at least 12 months of follow-up data available after the initial claim. Patients were excluded if they were not continuously eligible for pharmacy benefits throughout this 18-month period. Published studies were used to estimate outpatient visit-related health care resource use, and costs for prescription medications and health care resource use were derived from standard, published benchmarks.Results:The database analysis identified 9398 patients meeting study criteria, 45% (n = 4230) of whom remained on their initial prostaglandin therapy for 12 months after initiation. Adjunctive intraocular pressure lowering therapy was needed in 23.6%, 18.5%, and 13.3% of bimatoprost, latanoprost, and BAK-free travoprost patients, respectively. Median numbers of days to the first prescription filled for adjunctive therapy (if required) were 72.5, 74.0, and 125.0 for patients initiating on bimatoprost, latanoprost, and BAK-free travoprost. Total estimated first-year costs were $1973, $1807, and $1739 for patients initiating therapy with bimatoprost, latanoprost, and BAK-free travoprost. Findings were consistent through sensitivity analysis.Conclusions:A BAK-free prostaglandin analog may permit longer duration of monotherapy and be associated with lower first-year direct treatment costs. Use of a claims database and the selection of new initiators of prostaglandin analogs limit projecting findings to all glaucoma patients.