Date of Award

January 2026

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Nihar Desai

Abstract

Background:Atherosclerotic cardiovascular disease is a leading cause of mortality in the United States and has well-documented disparities in identification, treatment, and outcomes among different populations. Despite numerous lipid-lowering therapeutic options approved in recent years, patient access to these novel medications remains limited, particularly in the Medicare population of over 69 million beneficiaries. In order to improve guideline-concordant use of lipid-lowering therapies, it is critical to understand barriers to medication accessibility and how they have evolved with recent health policy changes such as the Inflation Reduction Act of 2022.

Research Aims:We aim to understand how Medicare prescription drug plan coverage, restrictions such as prior authorization and step therapy, and patient costs for lipid-lowering therapies vary on a state-by-state basis. We further explore patient cost by examining the payment structures of Medicare plans, focusing on tier-based cost-sharing, requirements of coinsurance rather than a fixed co-payment, coinsurance amounts, monthly costs, and medication list prices without insurance. We consider how payment structures and costs of lipid-lowering therapies have changed with the evolving architecture of Medicare plans between 2023 and 2025, coinciding with the introduction of the Inflation Reduction Act.

Question:How did state-level disparities in Medicare patient access to lipid-lowering therapies change from 2023 to 2025 with the implementation of the Inflation Reduction Act?

Methods:This analysis used Quarterly Medicare Prescription Drug Plan Formulary and Pricing files from Quarter 3 of 2023 and Quarter 3 of 2025. Medications of interest included non-generic lipid-lowering therapies such as pro-protein convertase subtilisin-kexin type 9 inhibitors (alirocumab and evolocumab) and bempedoic acid. For each medication, the percentage of plans providing coverage and the proportion of covering plans requiring restrictions including prior authorization and step therapy were assessed. The monthly and annual out-of-pocket costs were calculated for each medication, with further exploration into the drivers of cost including the proportion of plans requiring high-tier cost-sharing (≥ tier 3 or ≥ tier 4), mandates of coinsurance rather than a fixed co-payment during the coverage phase, coinsurance amounts, and medication list prices without insurance. All results were stratified among the 50 states, with temporal trends studied between Quarter 3 of 2023 and Quarter 3 of 2025.

Results:Between Quarter 3 of 2023 and Quarter 3 of 2025, the number of Medicare prescription drug plans decreased from 4,754 to 4,175. On a national level, coverage increased for bempedoic acid (33% to 61%) and evolocumab (72% to 92%), but decreased for alirocumab (54% to 12%), with differences on a state-by-state basis. Barriers including prior authorization and step therapy were observed to vary between states. Median annual out-of-pocket costs rose for bempedoic acid and alirocumab but decreased for evolocumab, with the third quartile of payments increasing for all three medications and approaching the $2,000 cap. In 2025, beneficiaries in states requiring the highest median annual out-of-pocket cost paid nearly twice as much as those in states with the lowest median annual out-of-pocket cost for all three medications. Coinsurance requirements increased between 4 and 10-fold for all three therapies, reflecting overall changes between 2023 and 2025 in the framework of Medicare prescription drug plans favoring coinsurance rather than co-payment for cost-sharing of high-tier medications.

Scientific Impact:Despite the high clinical burden of atherosclerotic cardiovascular disease and known inequities, Medicare beneficiaries continue to face substantial administrative and financial barriers to guideline-concordant lipid-lowering therapies. This analysis comparing 2023 and 2025 Medicare prescription drug plans particularly highlights worsening state-level discrepancies in coverage, access barriers, out-of-pocket payments, and drivers of cost such as rising coinsurance requirements. These findings suggest that implementation of the Inflation Reduction Act has coincided with an increased variability in state-level lipid-lowering therapy access, which may continue to exacerbate pre-existing disparities in cardiovascular risk among Medicare beneficiaries. This study has relevance on an everyday basis in medicine, as physicians must understand how to work within the constraints of the insurance system to deliver care that is effective, equitable, and accessible.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 07/14/2028

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