Abstract
Abstract: :
Purpose: To investigate patient persistency with several classes of topical intraocular pressure lowering medications. Methods: Using medical claims data from a large US health insurer, we selected patients newly diagnosed with suspected glaucoma (i.e., ocular hypertension or borderline glaucoma) or glaucoma (based on ICD–9 diagnostic codes) who initiated therapy with a topical ocular hypotensive medication between July 1995 and December 2001. Five classes of medications were investigated: beta adrenergic blockers, alpha adrenergic agonists, miotics, carbonic anhydrase inhibitors, and prostaglandin analogs. At each 6–month interval for up to 3 years after the start of treatment, we calculated the proportion of patients who refilled the initially prescribed medication. These calculations were performed using 3 values of supply times of the dispensings (60, 90, and 180 days) to allow a view of persistency using definitions of continuous therapy that varied in strictness and allowed for patient variability in adherence to the prescribed dosing regimen. Proportions were computed separately for each class of medications and by glaucoma diagnosis (suspect vs. diagnosed). We also examined the proportion receiving a dispensing of any topical medication, allowing for changes from the originally prescribed drug. Results: A total of 3822 patients, 1104 glaucoma suspects and 2718 patients diagnosed with glaucoma, met all eligibility criteria for the study. The proportion of patients receiving a refill of their initial medication within 60 days of their last dispensing at any time point ranged from approximately 20–50%, with prostaglandin analogs showing the greatest persistency of any class. No clear patterns emerged with respect to time since treatment initiation. Glaucoma suspects showed persistency levels that were lower by up to 10% compared with diagnosed patients, with many comparisons achieving significance at the 0.05 level. Persistency with any ocular hypotensive medication, not restricted to the initially dispensed drug, varied from 45–59% and again was higher among diagnosed patients than suspects. Conclusions: Patients with diagnosed glaucoma demonstrated low persistency, and glaucoma suspects even lower persistency, with their topical ocular hypotensive therapy. Both changes in medication and discontinuation of therapy occurred with high frequency. Patients initially prescribed a prostaglandin analog showed greater treatment persistency than those dispensed other classes of ocular hypotensives.
Keywords: clinical (human) or epidemiologic studies: health care delivery/economics/manpower • clinical (human) or epidemiologic studies: outcomes/complications