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S. Kotak, G. F. Schwartz, G. Reardon, S. N. Shah; Persistence on Prostaglandin Ocular Hypotensive Therapy: An Assessment Using Medication Possession and Days of Coverage on Therapy. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3212.
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To evaluate persistence on prostaglandin therapy for glaucoma patients in the first therapy year.
Data was derived from the Ingenix managed care database. Patients who had latanoprost (LAT), bimatoprost (BIM), or travoprost (TRAV) dispensed during 1/1/04-12/31/04 were screened for inclusion. The 1st agent filled was identified as the index agent (fill date=index date). Follow-up continued for 358 days. Patients were excluded if they: 1) were <40 years old, 2) were not continuously enrolled for 180 days before/358 days after index date, 3) had an ocular hypotensive dispensed, or had no glaucoma diagnosis, within 180 days before index date. Persistence measures included: 1) whether the last fill in the 1st therapy year had sufficient days supply to achieve Medication Possession at year end, and 2) the number of days in the 1st therapy year for which a supply of index agent was available (Days Covered). Possible inconsistencies between quantity dispensed and days supply reported were addressed by multiplying original days supply on the claim with alternative measures derived from the literature. Logistic regression was used to evaluate the association of index agent with Medication Possession, and linear regression, with Days Covered. All models were adjusted for gender, age, and previous ocular hypertension diagnosis.
7,783 patients met all inclusion criteria (LAT, n=4994; BIM, n=1464; TRAV, n=1415). The odds of achieving Medication Possession at 1st therapy year’s end declined by 26%-34% for BIM, and declined by 34%-36% for TRAV, compared to LAT users (p≤0.001 for all comparisons for each imputation method). Days Covered during the 1st therapy year were 21-29 days lower for BIM, and 33-42 days lower for TRAV, compared to LAT (p≤0.001 for all comparisons). Additional analysis showed that, for all agents, a failure to refill a 2.5 ml size within the first 90 days had 90%-99% specificity for predicting low persistence (<75% Days Covered) across the 1st therapy year.
Persistence on ocular prostaglandin therapy continues to remain a concern. LAT users had higher odds of achieving Medication Possession and more Days Covered during the 1st therapy year. A failure to refill the index agent within the 1st 90 days appears to be a strong predictor of poor persistence for the therapy year.
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