Medication Adherence and Visual Field Progression in CIGTS
Ophthalmology, April 2020
The Collaborative Initial Glaucoma Treatment Study (CIGTS) compared the effect of initial treatment with topical medications to that of trabeculectomy in 607 patients with newly diagnosed glaucoma. Of these, 307 were randomized to the medication arm of the study and underwent regular assessment of their medication adherence and disease progression. Newman-Casey et al. reported long-term data on these patients; they found a statistically and clinically significant association between medication nonadherence and visual field (VF) loss.
The patients were followed up at six-month intervals for an average of 7.3 years. Medication adherence was assessed via telephone calls in which patients were asked, “We want to get an idea of what medication taking is like for you. Did you happen to miss any dose of your [name of medication] yesterday (yes or no)?” 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 at which a missed dose of medication was reported.
Adherence data were available for 306 of the 307 patients. Of these, 142 (46%) reported never missing a dose of medication, 112 (37%) reported missing medication at up to one-third of visits, 31 (10%) reported missing medication at one-third to two-thirds of visits, and 21 (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 patients who reported never missing a dose of medication, the average predicted MD loss over eight years was 0.62 decibels (dB), consistent with age-related loss (95% confidence interval [CI], 0.17-1.06; p = 0.007). Patients 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 those 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).
The authors noted that 79% of participants had five years of follow-up data, thus offering unique insights into the association between medication-taking behavior and the progression of VF loss.
The original article can be found here.