Effect of generic glatiramer acetate on spending and use of drugs for multiple sclerosis

To estimate changes in costs and utilization trends for disease-modifying therapies (DMTs) from 2011 to 2017 in the US Medicaid program.

Using quarterly Medicaid State Drug Utilization Data from 2011 to 2017, we summarize trends in spending, utilization, and costs per prescription for 15 multiple sclerosis (MS) DMTs including brand and generic versions of glatiramer acetate. We use interrupted time series regression to estimate the effect of market entry of generic glatiramer acetate on cost per prescription of other self-administered DMTs.

Gross annual expenditures on MS DMTs increased from $453 million to $1.32 billion between 2011 and 2017 within the Medicaid program. Increased spending was primarily driven by increases in per prescription costs, which doubled during the study period. Although total utilization was stable, product specific utilization shifted from injectable to oral DMTs. However, throughout the study, the plurality of utilization was glatiramer acetate. The introduction of generic glatiramer acetate in Q2 of 2015 was associated with an immediate increase of $441 (95% confidence interval [CI] $184-$697; p < 0.001) in the cost per prescription of branded glatiramer acetate followed by a gradual $52 per prescription reduction (95% CI -$86 to -$18) over time. There were minimal changes in the costs for the other DMTs.

Spending on MS DMTs in the Medicaid program have more than doubled over the last 7 years primarily as a function of higher costs per prescription. Introduction of a generic glatiramer acetate product in 2015 had nominal effects on overall price trajectories and utilization within the class.