The Effect of Medication Adherence on Intraocular Pressure and Glaucoma Progression.

PURPOSE

Little is known about how medication adherence is related to longitudinal structural and functional losses. Here, we investigate the associations between medication adherence with mean intraocular pressure (IOP) measurements, explore whether adherence predicts rates of change in mean deviation (MD) and retinal nerve fiber layer thickness (RNFLT), and identify factors associated with worse adherence using a large sample of glaucoma and glaucoma suspect eyes.

DESIGN

A retrospective longitudinal cohort study.

PARTICIPANTS

Adults with glaucoma or glaucoma suspect status in at least 1 eye, defined by ICD code H40. All eyes had a minimum of five visual field or OCT tests over time.

METHODS

Proportion of days covered (PDC), defined as the proportion of days a patient has access to their medication over a given period using pharmacy refill data, was used to assess adherence. Multivariable linear mixed-effects models were used to investigate the relationship between PDC with mean IOP and rates of change in both MD and RNFLT. Similar models were employed to examine predictors of PDC.

MAIN OUTCOME MEASURES

Mean IOP, rates of change in MD, and RNFLT.

RESULTS

A total of 13 670 eyes from 8163 patients were included with a median (interquartile range) PDC of 60 (40.9-77.5). Below the 60% adherence threshold (median), each 10% decrease in PDC was associated with higher mean IOP (β = 0.82 mmHg, P < 0.001), while the association showed a smaller effect size above the median (β = 0.37 mmHg, P < 0.001). Proportion of days covered was associated with -0.03 units/year faster rates of MD and RNFLT loss (P < 0.01). Predictors of worse PDC included female gender (β = -1.22%, P = 0.02; vs. males), Black race (β = -5.04%, P < 0.001; vs. White), worse baseline MD (β = -0.23%, P = 0.01; per 5 decibel decrease), lower baseline RNFLT (β = -0.17%, P = 0.03; per 10 μm thinner), using two eye drops (β = -6.37%, P < 0.001; vs. 1), and unilateral drop use (β = -8.85%, P < 0.001; vs. bilateral).

CONCLUSIONS

Lower adherence was associated with higher IOP, with a stronger effect seen at PDC values below the median, and accelerated glaucomatous damage, including faster rates of MD deterioration and increased RNFLT loss. Lower adherence was associated with female gender, Black race, greater baseline damage, greater number of drops, and unilateral drop use. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.