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Mariam Salman, Justin Gatwood, Paula Anne Newman-Casey; Modeling the societal costs of poor glaucoma medication adherence. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1986.
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At least half of people diagnosed with glaucoma do not take their prescribed medications though these medications have been proven to decrease glaucoma related vision loss. Poor medication adherence remains an important contributor to why glaucoma remains a leading cause of blindness in the US and worldwide. We modeled the costs and utilities of glaucoma medication adherence to develop a tool from which to better understand its societal impact.
A cost-utility analysis using microsimulation (10,000 iterations) estimated glaucomatous progression based on data from the recent United Kingdom Glaucoma Treatment Study (UKGTS).1 Participants with glaucoma entered the model at age 40 with a mean deviation in the better seeing eye of -1.4dB ±-1.9d and -4.3dB ± -3.4dB in the worse seeing eye. Participants who worsened each year accumulate -0.8Db loss compared to -0.1dB loss for those who remain stable. Data from the Glaucoma Laser Trial and the Trabeculectomy versus Tube Study were used to assign probabilities of worsening disease among treated patients. Data from a study that calculated rates of glaucoma medication adherence over four years was used to assign medication adherence values, and those with poor adherence were modeled as having outcomes similar to the placebo arm.2 As patients’ mean deviation deteriorated, they transitioned from mild (≥-6dB), to moderate (<-6dB to ≥-12dB), to severe glaucoma (<-12dB to ≥23dB) to unilateral (<-20dB) and bilateral blindness. At each health state, patients incurred the costs of treatment and established health utilities; ultimately, societal costs of low vision and blindness were included.
Cumulative incidence of blindness was 15.5% and 26.6% among adherent and nonadherent patients, respectively. Mean costs incurred for the adherent cohort were $51,938 ± 39,3122 (median: $44,077) versus $51,960 ± $45,318 (median value $36,707) for the nonadherent cohort (p=0.971). Compared to those nonadherent to therapy, those adherent gained 0.75 quality-adjusted life-years (QALY) over the 60 years of simulation, resulting in an incremental cost-effectiveness ratio of -$29.15 per QALY.
Economic modeling demonstrates the poorer health-related quality of life among poorly adherent glaucoma patients modeled from age 40. Further work could estimate the population level impact of poor glaucoma medication adherence and the potential impact of tailored patient counseling.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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