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

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.

An ecologic observational study using state-year-level data.

Medicare Part D beneficiaries receiving glaucoma medications across 50 states and the District of Columbia from 2019 through 2023 (255 state-years).

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.

Spending per beneficiary and spending per claim.

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% confidence interval [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.

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.

The authors have no proprietary or commercial interest in any materials discussed in this article.