Broader Formulary Coverage Linked to Lower Risk of MS Relapse

When drug formularies included a broader selection of disease-modifying therapies (DMTs), patients saw up to a 12% reduction in their odds of experiencing a multiple sclerosis (MS) relapse. Researchers suggested formulary coverage should be designed to favor patient needs rather than managing cost and use, according to data from a study published in JAMA Network Open.¹

“In the US, pharmacy benefit managers (PBMs) use a variety of tools to leverage discounts and rebates from pharmaceutical manufacturers,” wrote the authors. “These measures include placing medications on preferred or nonpreferred cost-sharing tiers, restricting access with use management requirements, and excluding medicines from formularies altogether.”

PBM formulary design is crafted to ensure patients receive safe, effective, and affordable medication options. However, many experts claim PBMs are doing the opposite, driving patients toward more out-of-pocket costs and fewer medication options to treat their disease states. Furthermore, PBM opponents and advocates for reform have argued that these middlemen are purposely manipulating formulary design to drive profits.

Researchers investigated how PBM implications can impact medication access, use, and potential outcomes for patients with MS. | image credit: WindyNight / stock.adobe.com

READ MORE: Top 3 PBMs Contribute to Over 1500% Increase in Formulary Exclusions Since 2014

Whether the intentions of their actions are true or not, PBM practices have been significantly uncovered as of late, from 2 reports released by the Federal Trade Commission highlighting PBMs’ market control to more recent discoveries of the same PBMs increasing formulary exclusions by more than 1500% since 2014.^2-4

“When exclusions are applied to brand drugs with generic equivalents or within classes in which multiple drugs have similar treatment effects, the impact may be as intended (ie, use of more cost-effective or lower-net-cost drugs),” they continued.¹ “However, drugs that treat complex conditions such as cancers and autoimmune disorders, which are often characterized by heterogenous treatment effects across products and beneficiaries, are increasingly subject to formulary restrictions, such as greater cost-sharing or use management, which may be negatively associated with outcomes.”

While some drugs included in formularies can exist within the Medicare Part D protected drug classes—meaning drugs that must be exempt from formulary exclusions or restrictions⁵—DMTs to treat heterogenous conditions like MS are often subject to restrictions.

In their exploration of formulary exclusions and their impact on patient care, researchers investigated how PBM implications can impact medication access, use, and potential outcomes for patients with MS.

“Relapsing-remitting MS is a good test case because while there are no current cures, an increasing number of DMTs are available and have been shown to help slow disease progression, reduce the number of relapses, and limit new disease activity,” they wrote.¹ “The objectives of this study were to document differences in formulary exclusions of MS DMTs in Medicare Part D and examine whether prior year enrollment in a more restrictive plan was associated with greater odds of MS relapse.”

Researchers explored Medicare administrative data between 2018 and 2022. Beneficiaries were included as study participants if they were a part of stand-alone prescription drug plans (PDPs) or Medicare Advantage prescription drug plans (MA-PDs). Furthermore, they were only included in the final analysis if beneficiaries reported use of relapsing-remitting MS and baseline MS DMTs. Each participant’s outcomes were followed for a total of 1 year and 3 months.

There were 50,162 participants with PDPs (mean age, 58.5 years old; 74.9% women) and 34,708 with MA-PDs (mean age, 58.2 years old; 77.2% women).

“As the number of MS DMTs has increased, formulary coverage has become more restrictive in both PDPs and MA-PDs. We found a negative association between formulary coverage of MS DMTs and the odds of MS relapse among Medicare beneficiaries,” the authors wrote.¹ “Broader formulary coverage in MA-PDs was associated with an 8% to 12% lower odds of MS relapse during follow-up and a 6% to 9% lower odds in PDPs.”

Despite the introduction of various new DMTs for diseases like MS, formulary exclusions continue to increase and are translating into exacerbated outcomes.^1-2 When it comes to PBM reform and the changes advocates are calling for, results of this study underscore patients’ inability to access life-saving medications. The focus of formulary exclusions and inclusions should be more geared toward patients’ health-related needs.

“Health plans and PBMs have been relying on formulary exclusion to limit costs of new therapies,” they concluded.¹ “However, a more nuanced approach that also accounts for patient benefit (and potential harm) should also be considered.”

READ MORE: Where PBM Reform is Headed in 2025, Beyond | NCPDP 2025

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References

1. Blaylock B, Van Nuys K, Joyce G. Formulary restrictions and relapse episodes in persons with relapsing-remitting multiple sclerosis. JAMA Netw Open. 2025;8(8):e2525155. doi:10.1001/jamanetworkopen.2025.25155

2. Nowosielski B. Top 3 PBMs contribute to over 1500% increase in formulary exclusions since 2014. Drug Topics. August 1, 2025. https://www.drugtopics.com/view/top-3-pbms-contribute-to-over-1500-increase-in-formulary-exclusions-since-2014

3. FTC releases interim staff report on prescription drug middlemen. News Release. Federal Trade Commission. July 8, 2024. Accessed August 4, 2025. https://www.ftc.gov/news-events/news/press-releases/2024/07/ftc-releases-interim-staff-report-prescription-drug-middlemen

4. FTC releases second interim staff report on prescription drug middlemen. News Release. Federal Trade Commission. January 14, 2025. Accessed August 4, 2025. https://www.ftc.gov/news-events/news/press-releases/2024/07/ftc-releases-interim-staff-report-prescription-drug-middlemen

5. Medicare Advantage and Part D drug pricing final rule (CMS-4180-F). Centers for Medicare & Medicaid Services. May 16, 2019. https://www.cms.gov/newsroom/fact-sheets/medicare-advantage-and-part-d-drug-pricing-final-rule-cms-4180-f