Costs of Potential Medication Wastage Due to Switching Treatment Among People With Multiple Sclerosis.

Background: Unused medications negatively impact healthcare resource utilization and environmental safety, contribute substantially to annual healthcare expenditures, and may ultimately affect patient health outcomes. People with multiple sclerosis (PwMS) commonly switch disease-modifying therapies (DMTs), leading to medication wastage and substantial costs for insurers and patients. Objectives: To estimate the cost associated with potential medication wastage (PMW) in a subcohort of PwMS receiving oral or self-injectable US Food and Drug Administration-approved DMTs who switched DMTs in a calendar year in the United States. Methods: This retrospective cohort study included adults with MS and used PharMetrics® Plus claims data from 2017 to 2021. PwMS were required to have 12 months of continuous eligibility for the entire year and a claim for at least 2 unique DMTs during the same calendar year. The PMW cohort was defined as those who had an aggregate overlap in days' supply across DMT switches within the year; those in the non-PMW cohort did not. The cost of PMW for insurers and PwMS due to overlap was calculated only at the point of switch to the new DMT and defined as the cost of the remaining days' supply of the prior DMT. Results: The number of PwMS meeting the inclusion criteria was 1762 in 2017, 1947 in 2018, 1679 in 2019, 1461 in 2020, and 1782 in 2021. Approximately 95% of PwMS switched DMTs once within single calendar years, and 25% (n = 381-464) contributed to PMW. For those who had overlapping DMT supply, it was estimated that 34% to 38% of the DMT being switched from was potentially wasted. The total cost of PMW paid by the insurer and PwMS ranged from $1 200 866to$ 1 489 859. While most of the total cost ( $1\hspace{0.17em}172\hspace{0.17em}140-$ 1 450 328) was paid by the insurer, PwMS still owed substantial amounts ( $28 726-$ 74 578). Across all PwMS, the per person per year cost ranged from $716to$ 846. The estimated wastage and associated costs were consistent across all study years. Conclusions: DMT switching is common among PwMS, resulting in PMW and high costs to patients and insurers.