Medication Adherence and Visual Field Progression in Patients With Glaucoma
abstract
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Access this abstract now Full Text Available for ClinicalKey SubscribersPURPOSE
To evaluate the relationship between medication adherence and visual field progression in participants randomized to the medication arm of the Collaborative Initial Glaucoma Treatment Study (CIGTS).
DESIGN
The CIGTS was a randomized, multicenter clinical trial comparing initial treatment with topical medications to trabeculectomy for 607 participants with newly diagnosed glaucoma.
PARTICIPANTS
Three hundred seven participants randomized to the medication arm of the CIGTS.
METHODS
Participants were followed up at 6-month intervals for up to 10 years. Self-reported medication adherence and visual fields were measured. Medication adherence was assessed by telephone from responses to the question, "Did you happen to miss any dose of your medication yesterday?" The impact of medication adherence on mean deviation (MD) over time was assessed with a linear mixed regression model adjusting for the effects of baseline MD and age, cataract extraction, interactions, and time (through year 8, excluding time after crossover to surgery). Medication adherence was modeled as a cumulative sum of the number of prior visits where a missed dose of medication was reported.
MAIN OUTCOME MEASURE
Mean deviation over time.
RESULTS
Three hundred seven subjects (306 with adherence data) were randomized to treatment with topical medications and followed up for an average of 7.3 years (standard deviation, 2.3 years). One hundred forty-two subjects (46%) reported never missing a dose of medication over all available follow-up, 112 patients (37%) reported missing medication at up to one third of visits, 31 patients (10%) reported missing medication at one third to two thirds of visits, and 21 patients (7%) reported missing medication at more than two thirds of visits. Worse medication adherence was associated with loss of MD over time (P = 0.005). For subjects who reported never missing a dose of medication, the average predicted MD loss over 8 years was 0.62 dB, consistent with age-related loss (95% confidence interval [CI], 0.17-1.06; P = 0.007); subjects who reported missing medication doses at one third of visits had a loss of 1.42 dB (95% CI, 0.86-1.98; P < 0.0001); and subjects who reported missing medication doses at two thirds of visits showed a loss of 2.23 dB (95% CI, 1.19-3.26; P < 0.0001).
CONCLUSIONS
This longitudinal assessment demonstrated a statistically and clinically significant association between medication nonadherence and glaucomatous vision loss.
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Additional Info
Disclosure statements are available on the authors' profiles:
The Association Between Medication Adherence and Visual Field Progression in the Collaborative Initial Glaucoma Treatment Study
Ophthalmology 2020 Jan 10;[EPub Ahead of Print], PA Newman-Casey, LM Niziol, BW Gillespie, NK Janz, PR Lichter, DC MuschFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The strength of this study is that it is part of the Collaborative Initial Glaucoma Treatment Study (CIGTS), a longitudinal randomized clinical trial. A weakness of the study is that, to determine adherence it relied on patient self-reports, which are notoriously unreliable when relaying information relative to compliance with obtaining, let alone taking, one's medication. In this case, the key question asked on each of the 6-month interval follow-ups was: "Did you happen to miss any dose of your medication yesterday?" It's a clever way to be casual rather than accusatory, and presumably elicits a more forthcoming answer. Adherence was determined by the cumulative sum of positive answers to that question through year 8. In other words, adherence was determined by how many times the participants reported missing a dose of medication during the 15 visits when they were asked the question. If one accepts that as a valid index, then those patients who reported never missing a dose experienced an average loss of dB on visual fields over the time period of the study that was consistent with what would be expected from aging. Those who reported missing doses at one-third of the visits doubled that rate of loss, and those who reported missing doses at two-thirds of their visits tripled that rate. The conclusion is that there is both a statistically and clinically significant relationship between medication nonadherence and glaucomatous vision loss.