title: Medical service encounters and payments associated with topical adjunctive therapy use of timolol for glaucoma.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  To evaluate inpatient and outpatient service encounters and payments associated with the topical adjunctive use of the β-blocker timolol for glaucoma.
  
  
  METHODS
  Retrospective data analysis using 2004-2011 IMS Lifelink Health Plan Claims Database.
  
  
  METHODS
  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 4 years of continuous enrollment and glaucoma medication use (defined as at least one pharmacy claim each year). Beneficiaries who had 4 years of observation with no timolol use were categorized as "controls" and those with 2 years of non-timolol glaucoma medication use followed by consecutive years of adjunctive timolol use were considered "cases." Beneficiaries with 2 years of non-timolol glaucoma medication use followed by 1 year in which they used timolol adjunctively and then a year without timolol use were considered "discontinuers."
  
  
  METHODS
  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.
  
  
  RESULTS
  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 65 years 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 65 years 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 65 years of age. Among those aged 65 years 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Exponent Inc., Alexandria, VA 22314, USA. jschmier@exponent.com
authors.forename: Jordana K
authors.initials: JK
authors.lastname: Schmier
authors.forename: David W
authors.initials: DW
authors.lastname: Covert
authors.forename: Edmund C
authors.initials: EC
authors.lastname: Lau
mesh_terms: D060433:Administration, Ophthalmic; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000367:Age Factors; D000368:Aged; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology; D016208:Databases, Factual; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy*; D017048:Health Care Costs; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D012140:Respiratory Tract Diseases / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D013997:Time Factors; D013999:Timolol / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000319:Adrenergic beta-Antagonists; D013999:Timolol