Variation in Medicare Part D and Part B drug spending among older adults with Alzheimer's disease and related dementias.

Background and Objectives: This study examined Medicare Part D and Part B drug spending and beneficiary out-of-pocket (OOP) costs among community-dwelling Medicare fee-for-service (FFS) beneficiaries with Alzheimer's disease and related dementias (ADRD), assessing variation by dual eligibility, state, and Accountable Care Organization (ACO) enrollment. Research Design and Methods: We conducted a cross-sectional analysis using the 2022 Medicare Beneficiary Summary File linked to the Cost and Use file. The sample included 1 372 696 community-dwelling Medicare FFS beneficiaries with ADRD, including 575 308 beneficiaries with five or more chronic conditions. Outcomes included annual Medicare payments and beneficiary OOP costs for Parts D and B drugs. Analyses were stratified by dual eligibility duration, state, and ACO enrollment, with adjusted estimates from generalized linear models. Results: Medicare Part D drug spending was substantial, increasing with dual-eligibility duration: $8732-$9107 among beneficiaries with full-year dual eligibility and exceeding $11 500 among those with 5+ chronic conditions. Beneficiary OOP costs were highest among Medicare-only beneficiaries and markedly lower among dually eligible individuals. Medicare Part B drug spending was highest among Medicare-only beneficiaries and varied widely by state, ranging from $433 to $1827 among Medicare-only beneficiaries and from $179 to $1446 among dually eligible beneficiaries. After adjustment, differences in Parts D and B drug spending by ACO enrollment were modest. Discussion and Implications: Parts D and B drug costs among Medicare beneficiaries with ADRD vary by dual eligibility and geography. Limited associations with ACO enrollment underscore the need for better medication management integration in value-based care for high-need older adults with ADRD.