The effect of Medicaid expansion on prescriptions for breast cancer hormonal therapy medications

Objective: To quantify the effects of the Affordable Care Act Medicaid expansion on prescriptions for effective breast cancer hormonal therapies (tamoxifen and aromatase inhibitors) among Medicaid enrollees. Data Source/Study Setting: Medicaid State Drug Utilization Database (SDUD) 2011-2018, comprising the universe of outpatient prescription medications covered under the Medicaid program. Study Design: Differences-in-differences and event-study linear models compare population rates of tamoxifen and aromatase inhibitor (anastrozole, exemestane, and letrozole) use in expansion and nonexpansion states, controlling for population characteristics, state, and time. Principal Findings: Relative to nonexpansion states, Medicaid-financed hormonal therapy prescriptions increased by 27.2 per 100 000 nonelderly women in a state. This implies a 28.8 percent increase from the pre-expansion mean of 94.2 per 100 000 nonelderly women in expansion states. The event-study model reveals no evidence of differential pretrends in expansion and nonexpansion states and suggests use grew to 40 or more prescriptions per 100 000 nonelderly women 3-5 years postexpansion. Conclusions: Medicaid expansion may have had a meaningful impact on the ability of lower-income women to access effective hormonal therapies used to treat breast cancer.