Socioeconomic Differences in Glaucoma Medication Spending Under Medicare Part D: Evidence on Price vs Utilization

Objective To examine whether socioeconomic differences in Medicare Part D glaucoma medication spending are more strongly associated with price exposure (spending per claim) than with utilization intensity. Design Ecologic observational study using state-year–level data. Participants Medicare Part D beneficiaries receiving glaucoma medications across 50 states and the District of Columbia from 2019 through 2023 (255 state-years). Methods We analyzed Centers for Medicare & Medicaid Services Medicare Part D Prescribers-by-Geography and Drug public use files. State-level socioeconomic context was measured using Area Deprivation Index (ADI) national rank and median household income (sensitivity analysis). Outcomes included inflation-adjusted spending per beneficiary and per claim, as well as utilization measures (claims and 30-day fills per beneficiary) and brand spending and claims shares. Multivariable linear regression models included year fixed effects and state-clustered standard errors. Main Outcome Measures Spending per beneficiary and spending per claim. Results Median spending per beneficiary was $403.81 (interquartile range [IQR], $359.74–$444.73), and median spending per claim was $104.22 (IQR, $89.49–$118.41). Higher median household income was associated with greater spending per beneficiary ($18.18 per $10,000; 95% CI, $1.30–$35.06) and per claim ($6.99; 95% CI, $1.95–$12.03). Higher ADI was associated with lower spending per claim, although estimates were imprecise (–$3.69 per 10-point increase; 95% CI, –$7.51 to $0.13). Utilization intensity varied minimally across socioeconomic strata (claims per beneficiary, 3.8–4.0), and neither ADI nor income was consistently associated with brand spending or claims share. Conclusions State-level socioeconomic context was associated with modest differences in glaucoma medication spending per claim, with minimal differences in utilization intensity. These findings suggest that socioeconomic variation in Medicare Part D glaucoma drug spending is more consistent with differences in price exposure than with differences in volume of use.