To evaluate state-level variation in Medicaid (i) coverage, and (ii) real-world utilization of high-efficacy disease-modifying therapies (HETs) for multiple sclerosis (MS), and assess how formulary design influences access.

We combined data from two complementary analyses. First, we evaluated 462 Medicaid PDLs (412 Managed Care Organization [MCO], 50 Fee-for-Service [FFS]) for 2024 to quantify coverage generosity (≥2 HETs listed as preferred) and consistency (≥1 HET listed). Second, we analyzed the 2024 Medicaid State Drug Utilization Data for 27 FDA-approved MS therapies, to calculate state-level drug-utilization ratios (DUR). Regression models linked PDL generosity to DURs, adjusting for Medicaid expansion, enrollment, and MCO penetration.

PDL analyses revealed substantial geographic and plan-level variation, with clusters of restrictive formularies in the Midwest and South. 42% of Medicaid plans lacked any HET, and only 24.7% listed ≥2 HETs. Nine states had no plan with any HET as preferred. 

In utilization analyses, there was wide variation in HET utilization – some states demonstrating high uptake of anti-CD20 therapies, while others (e.g. Kentucky, West Virginia) more on lower-moderate efficacy DMTs. After adjustment, patients in MCO plans had 17.9% lower likelihood of HET use (β=−0.178; 95% CI=−0.33,−0.02; p=0.026), compared to FFS plans.

Significant variability in Medicaid drug formularies corresponds to disparities in real-world use of high-efficacy MS therapies. Policy efforts harmonizing coverage criteria across states and plans may reduce inequities and promote timely, effective treatment for Medicaid enrollees.