FORMULARY EXCLUSIONS AND NON-ADHERENCE TO DISEASE-MODIFYING THERAPIES FOR MULTIPLE SCLEROSIS IN MEDICARE PART D
Author(s)
Matthew Klebanoff, MD, MSHP1, Zhi Geng, MPH1, Pengxiang Li, PhD1, Salim Chahin, MD, MSCE2, Jalpa Doshi, PhD1;
1University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA, 2Washington University School of Medicine, St. Louis, MO, USA
1University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA, 2Washington University School of Medicine, St. Louis, MO, USA
OBJECTIVES: Medicare Part D plan formularies increasingly exclude disease-modifying therapies (DMTs) for multiple sclerosis (MS). Beneficiaries may access off-formulary drugs by submitting formulary exception requests that, when approved, last through the plan year. This hassle may lead to disruptions in DMT use and contribute to worse disease control. This study examined prevalence of off-formulary DMT use and investigated associations between off-formulary DMT use and adherence.
METHODS: This retrospective cohort study used 2017-2018 100% fee-for-service Medicare claims and Part D plan, formulary, and pharmacy characteristics files. The study sample included continuously eligible beneficiaries with MS diagnoses in 2017 and a DMT fill between 01/01/2018 to 06/30/2018 (index DMT=first DMT filled during this period). We determined whether each beneficiary’s index DMT was on or off-formulary based on their plan’s formulary information. The outcome was adherence to the index DMT measured as the proportion of days covered (PDC)≥0.8 during the 6-month post-index period. Using logistic regression, we examined associations between off-formulary use and adherence, adjusted for sociodemographic, health, plan, and pharmacy characteristics.
RESULTS: Among 31,985 beneficiaries, 36.0% used index DMTs that were off-formulary. Off-formulary use varied across DMTs, ranging from 1.6% among all fingolimod users to 86.9% among peginterferon beta-1a users. Off-formulary use was associated with lower odds of adherence to several DMTs, including teriflunomide (OR 0.80; 95% CI, 0.66-0.96), interferon beta-1a (subcutaneous) (OR 0.71; 95% CI, 0.56-0.92), interferon beta-1a (intramuscular) (OR 0.84; 95% CI, 0.71-0.98), glatiramer acetate (generic) (OR 0.63; 95% CI, 0.42-0.93), and glatiramer acetate (brand) (OR 0.53; 95% CI, 0.46-0.62).
CONCLUSIONS: Over one-third of Medicare beneficiaries with MS used DMTs that were off-formulary. Off-formulary use was associated with reduced adherence across several DMTs. Future research should elucidate the mechanisms by which formulary exclusions contribute to non-adherence to DMTs.
METHODS: This retrospective cohort study used 2017-2018 100% fee-for-service Medicare claims and Part D plan, formulary, and pharmacy characteristics files. The study sample included continuously eligible beneficiaries with MS diagnoses in 2017 and a DMT fill between 01/01/2018 to 06/30/2018 (index DMT=first DMT filled during this period). We determined whether each beneficiary’s index DMT was on or off-formulary based on their plan’s formulary information. The outcome was adherence to the index DMT measured as the proportion of days covered (PDC)≥0.8 during the 6-month post-index period. Using logistic regression, we examined associations between off-formulary use and adherence, adjusted for sociodemographic, health, plan, and pharmacy characteristics.
RESULTS: Among 31,985 beneficiaries, 36.0% used index DMTs that were off-formulary. Off-formulary use varied across DMTs, ranging from 1.6% among all fingolimod users to 86.9% among peginterferon beta-1a users. Off-formulary use was associated with lower odds of adherence to several DMTs, including teriflunomide (OR 0.80; 95% CI, 0.66-0.96), interferon beta-1a (subcutaneous) (OR 0.71; 95% CI, 0.56-0.92), interferon beta-1a (intramuscular) (OR 0.84; 95% CI, 0.71-0.98), glatiramer acetate (generic) (OR 0.63; 95% CI, 0.42-0.93), and glatiramer acetate (brand) (OR 0.53; 95% CI, 0.46-0.62).
CONCLUSIONS: Over one-third of Medicare beneficiaries with MS used DMTs that were off-formulary. Off-formulary use was associated with reduced adherence across several DMTs. Future research should elucidate the mechanisms by which formulary exclusions contribute to non-adherence to DMTs.
Conference/Value in Health Info
2026-05, ISPOR 2026, Philadelphia, PA, USA
Value in Health, Volume 29, Issue S6
Code
HPR78
Topic
Health Policy & Regulatory
Topic Subcategory
Insurance Systems & National Health Care
Disease
SDC: Neurological Disorders