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Sophia Ying Wang, Robert Chang; Reduction of Ocular Antihypertensive Medication Use After IStent Implantation in a Large U.S. Managed Care Network. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2045.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether implantation of the IStent trabecular micro-bypass shunt results in reduced use of ocular antihypertensive medications in a large healthcare claims database in the United States.
Individuals who underwent iStent implantation concurrent with cataract surgery from 2012-2016 were identified from claims records for a U.S. managed care network. Glaucoma diagnoses were identified by encounter billing codes, categorized into secondary glaucomas (including pigmentary and pseudoexfoliation), narrow angles, and primary open angle glaucoma (POAG). The number of different topical ocular antihypertensive agents used at baseline (0-4 months prior to first iStent surgery) and postoperatively (0-4, 4-8, 8-12, and 12-16 months after last iStent surgery) was determined from pharmacy records. Combination agents were counted as 2 agents. Multivariate Cox regression identified predictors for sustained reduced use of at least 1 topical glaucoma agent postoperatively, among patients who were on at least 1 agent preoperatively.
Among the 2971 eligible enrollees who underwent iStent implantation, 1509 and 1462 were bilateral and unilateral, respectively. Most had POAG (N=2329, 78.4%); 381 (12.8%) had narrow angles; 261 (8.8%) had secondary glaucoma. Thirty-eight patients (1.3%) were on oral carbonic anhydrase inhibitors (CAIs) preoperatively. At baseline, 1223 (41.2%) were on no topical glaucoma agents; 876 (29.5%), 437 (14.7%), and 435 (14.6%) were on 1, 2, or 3 or more topical agents, respectively. The proportion of patients on no drops increased postoperatively (62.5% at 12-16 months, P<0.0001, Chi-squared), and among those on at least 1 topical glaucoma agent at baseline, there was a mean reduction of 0.92 (95% CI 0.80-1.05) agents used at 12-16 months (P<0.0001, paired t-test). No patients used oral CAIs after surgery. Sustained reduction in glaucoma medication use postoperatively was more likely to be achieved by patients who underwent bilateral vs unilateral iStent implantation (HR 1.83, 95% CI 1.53-2.19), and by patients on 3 or more medications versus 1 medication at baseline (HR 1.68, 95% CI 1.36-2.09). Sex, age, and glaucoma diagnosis were not significantly associated with reduced glaucoma medication use.
Implantation of the iStent trabecular micro-bypass stent is associated with reduced use of topical ocular antihypertensives.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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