Abstract
Purpose :
To determine the effect of glaucoma medication adherence on visual field (VF) progression among newly diagnosed glaucoma patients taking intraocular pressure-lowering medication.
Methods :
Medication utilization and visual field data were assessed for patients with newly diagnosed glaucoma who filled a prescription within 90 days of diagnosis in 2001-2011. Pharmacy dispensary records were used to determine the medication proportion of days covered (PDC) in the year prior to each visual field, and averaged over the patient’s entire length of follow-up. Adherence was classified as low (0<PDC<20%), medium (20%≤PDC<80%), or high (80%≤PDC≤100%). Visual field data (mean deviation [MD]) were collected from Humphrey Visual Field machines and progression was defined as ≥ 3 dB loss from baseline. Multivariable analysis of probability of progression included covariates measuring age, sex, race/ethnicity, baseline severity, and history of stroke or diabetic retinopathy.
Results :
9,514 patients met study criteria; mean age was 66.3 years (SD = 10.8), 53.2% were male, and 30.7% White, non-Hispanic. At baseline, 38% patients had mild glaucoma (-2<MD < 2 dB); 40% moderate glaucoma (-6<MD≤ -2 dB), and 15% severe glaucoma (-12<MD ≤-6 dB). Patients with moderate to severe disease severity had greater risk of progression during follow-up (RR=1.15 and 1.47, p<0.001). At the end of follow-up, 8.4% of patients had low medication adherence, 44% moderate, and 48% high adherence. Among patients with high adherence, 31% of patients progressed, compared with 34% among patients with low or moderate adherence (p<0.001). After multivariable adjustment, low and moderate adherence remained significantly associated with VF progression (low, HR: 1.45, 95% CI: 1.22-1.73; moderate, HR: 1.35, 95% CI: 1.18-1.55) compared with patients with high adherence. The difference in progression between low and moderate adherers was not significant.
Conclusions :
In this study, patients with low or moderate medication adherence had a greater likelihood of VF progression than patients with high medication adherence (PDC≥80%). This risk persisted even after adjustment for factors such as age, sex, race/ethnicity, and baseline glaucoma severity. Additional research is needed to identify facilitators for and barriers to long-term medication adherence, particularly among patients presenting with moderate to severe glaucoma.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.