Medical Service Encounters and Payments Associated with Topical Adjunctive Therapy Use of Timolol for Glaucoma

Abstract

Topical β-blockers are commonly prescribed for primary open-angle glaucoma. Existing research is limited regarding respiratory or cardiovascular events that may result from using these topical β-blockers. To evaluate inpatient and outpatient service encounters and payments associated with the topical adjunctive use of the β-blocker timolol for glaucoma. Retrospective data analysis using 2004-2011 IMS Lifelink Health Plan Claims Database. Beneficiaries were included if they had a diagnosis of glaucoma (International Classification of Diseases-Ninth Revision-Clinical Modification [ICD-9-CM] code 365.xx) and at least 4years of continuous enrollment and glaucoma medication use (defined as at least one pharmacy claim each year). Beneficiaries who had 4years of observation with no timolol use were categorized as "controls" and those with 2years of non-timolol glaucoma medication use followed by consecutive years of adjunctive timolol use were considered "cases." Beneficiaries with 2years of non-timolol glaucoma medication use followed by 1year in which they used timolol adjunctively and then a year without timolol use were considered "discontinuers." The rates of respiratory and cardiovascular disease in year 2 of the observation period were compared to the rates in year 3, and healthcare encounters and payments were also compared. There were 24,271 glaucoma patients who did not receive timolol (controls), 1,406 beneficiaries who were prescribed timolol in addition to other glaucoma medications and continued its use (cases), and 299 beneficiaries who used adjunctive timolol for only a single year (discontinuers). More than half of each group was less than 65years of age (58% of controls, 53% of cases, 54% of discontinuers, p<0.05). The rate of respiratory disease increased in all groups from year 2 to year 3 of the observation period, with increases of 1.0%, 1.4% and 5.0% points among controls, cases and discontinuers, respectively (all between-group comparisons significant at p<0.05). There were similar changes in the rate of cardiovascular disease, with increases of 1.3%, 1.5% and 4.7% points among controls, cases and discontinuers, respectively (all between-group comparisons significant at p<0.05). These increases were generally lower for younger beneficiaries and greater for those 65years and older. Comparing years 2 and 3 of the observation period, discontinuers more than doubled their average rate of all-cause inpatient hospitalizations (0.35-0.83 encounters annually), while this rate remained steady for cases and controls (between-group comparisons significant at p<0.05). There was little change in this rate among patients less than 65years of age. Among those aged 65years and older, there was a substantial increase for discontinuers, with a tripling of the average annual rate of inpatient hospitalizations from 0.45 to 1.48 (all between-group comparisons significant at p<0.05). In this older group, both discontinuers and cases experienced more than a 20% increase in outpatient service encounters compared to only 9% for controls (all between-group comparisons significant at p<0.05). Overall, discontinuers would be expected to have average annual medical payments US$3,600 greater than controls and US$3,200 greater than cases. Adjunctive use of timolol by patients with glaucoma may be associated with increased respiratory and/or cardiovascular disease, hospitalizations and payments among patients for whom timolol may be contraindicated or who have yet undiagnosed manifestations of conditions for which it would be contraindicated.