Feasibility and Efficacy of a Mass Switch from Latanoprost to Bimatoprost in Glaucoma Patients in a Prepaid Health Maintenance Organization

Abstract

To assess the feasibility of an automatic switch of a large number of patients with glaucoma or suspicion of glaucoma from latanoprost to bimatoprost, and to compare the efficacy of the 2 prostaglandin analogs before and after the switch. Retrospective nonrandomized comparison. Forty-three thousand four hundred forty-one California patients and 538 patients at one Southern California clinical facility of a nationwide prepaid health maintenance organization (HMO) who were on either prostaglandin between March 2002 and December 2003 (21 months). Beginning in April 2002, patients on latanoprost were systemically switched to bimatoprost by the HMO pharmacy service after obtaining approval from the entire ophthalmology staff. PART 1: computerized dispensing records of California patients were retrieved. PART 2: medical records of patients at one clinical facility were reviewed. Rates of switching or switching back from one prostaglandin to another, intraocular pressure (IOP) control, and intolerability. PART 1: 17847 patients initially received latanoprost. Of them, 84.8% were switched from latanoprost to bimatoprost, and 13.0% were switched back to latanoprost. Twenty-five thousand five hundred ninety-four patients were started on bimatoprost without previous experience with latanoprost. Of them, 8.6% were later switched to latanoprost use instead. Patients who had previous experience with latanoprost had a statistically significantly higher rate of switching back to latanoprost after a period of bimatoprost use when compared with those who had no prior experience with latanoprost (13.0% vs. 8.6%, respectively; P<0.0001). PART 2: 309 patients were switched from latanoprost to bimatoprost. The mean IOP reduction of 0.51+/-2.77 mmHg (95% confidence interval, 0.20-0.82) after the switch was statistically significant (P = 0.001). Forty-one patients (13.3%) had a decrease of >3 mmHg of IOP. The statistical significance of the IOP reduction after the switch remains in the monotherapy group (P = 0.005) but not in the multitherapy group (P = 0.058). Thirty-three patients (10.7%) who were switched from latanoprost to bimatoprost discontinued bimatoprost and resumed latanoprost. A systematic pharmacy-level switch from latanoprost to bimatoprost in a nationwide HMO achieved a high switch rate, with little switching back. There was a small but statistically significant reduction in mean IOP after the switch. An appreciable proportion of patients switched had a clinically significant reduction of IOP.