July 2019
Volume 60, Issue 9
Free
ARVO Annual Meeting Abstract  |   July 2019
The Association between Glaucoma Medication Adherence and Intraocular Pressure Variability in the Collaborative Initial Glaucoma Treatment Study (CIGTS)
Author Affiliations & Notes
  • David C Musch
    Ophthalmology & Visual Sciences, Univ of Michigan-Kellogg Eye Ctr, Ann Arbor, Michigan, United States
  • Leslie Niziol
    Ophthalmology & Visual Sciences, Univ of Michigan-Kellogg Eye Ctr, Ann Arbor, Michigan, United States
  • Brenda W Gillespie
    Biostatistics, University of Michigan, Ann Arbor, Michigan, United States
  • Paula Anne Newman-Casey
    Ophthalmology & Visual Sciences, Univ of Michigan-Kellogg Eye Ctr, Ann Arbor, Michigan, United States
  • Footnotes
    Commercial Relationships   David Musch, Glaukos Corporation (R), InnFocus (R); Leslie Niziol, None; Brenda Gillespie, None; Paula Anne Newman-Casey, None
  • Footnotes
    Support  NEI Grant EY028997
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 1965. doi:
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    • Get Citation

      David C Musch, Leslie Niziol, Brenda W Gillespie, Paula Anne Newman-Casey; The Association between Glaucoma Medication Adherence and Intraocular Pressure Variability in the Collaborative Initial Glaucoma Treatment Study (CIGTS). Invest. Ophthalmol. Vis. Sci. 2019;60(9):1965.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To evaluate the relationship between medication adherence and intraocular pressure (IOP) variability in participants randomized to the medication arm of the CIGTS.

Methods : The CIGTS was a clinical trial of 607 newly diagnosed glaucoma patients randomized to treatment with topical medications or trabeculectomy. Participants were followed every 6 months up to 10 years. Visits included measures of IOP and self-reported medication adherence. Measures of IOP variability (maximum, range, and standard deviation [SD] over all prior visits) were calculated for years 3-8. Medication adherence was assessed by responses to “Did you happen to miss any dose of your medication yesterday?” The effect of adherence on IOP variability over time was assessed with linear mixed models (unadjusted and adjusted for education, baseline IOP and visual field). Adherence was modeled with a time-varying covariate summing the number of prior visits where a missed dose of medication was reported. Models excluded visits after trabeculoplasty or trabeculectomy.

Results : 307 subjects were randomized to medications and followed for an average of 7.3 years (SD=2.3). At 5 years, maximum, range, and SD of IOP were on average 22.4 mmHg (SD=3.7), 8.0 mmHg (SD=3.5), and 2.5 mmHg (SD=1.0), respectively. Measures of IOP variability were highly correlated (r=0.82 to 0.97). 148 subjects (48%) reported never missing a dose of their medication over all available follow-up. The numbers missing a dose for up to 1/3, 1/3 to 2/3, and >2/3 of visits were 105 (34%), 38 (12%), and 14 (5%), respectively. In unadjusted models, worse adherence was associated with higher maximum IOP (p=0.0154), larger range (p=0.0011), and increased SD (p=0.0821). In an adjusted model, adherence showed a significant effect on IOP range (p=0.0029). The average predicted increase in IOP range for a subject who reported missing a dose of medication at 1/3 of visits versus never reporting a missed dose was 0.8 mmHg (95% confidence interval, CI=0.3-1.4), whereas a subject missing medication doses at 2/3 of visits had an increase in IOP range of 1.8 mmHg (CI, 0.6-3.1). Similar associations of adherence with maximum IOP (p=0.0300) and SD of IOP (p=0.1297) were observed.

Conclusions : These results link medication non-adherence to increased IOP variability, which has been shown to be a risk factor for visual field loss.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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