Abstract

Objectives

To understand the nonlinear relationship between out-of-pocket (OOP) payments and disease-modifying treatment (DMT) use and adherence, primarily to pinpoint the threshold at which the use of DMTs becomes price sensitive.

Methods

Individuals with more than two multiple sclerosis (MS) diagnoses (International Classification of Diseases, Ninth Revision code 340) were identified from the MarketScan database (2006–2009). Heterogeneity in treatment was normalized by calculating an annual OOP payment as the average OOP payment for purchasing a fixed basket of DMTs at the insurance plan level. A local linear regression with a model-based recursive partitioning algorithm was applied to explore the relationship between OOP and consequently lower DMT use and adherence as measured by days covered by DMT.

Results

We identified the inflection points in annual OOP payments as $442 for DMT use and $890 for DMT adherence. For patients with annual OOP payments of more than $442, a $100-increase in OOP payment was associated with a decline of 0.6% in DMT use; for annual OOP payments of more than $890, a $100-increase in OOP payment was associated with two fewer days of DMT treatments.

Conclusions

Although the use of DMTs and DMT adherence appeared unassociated with OOP payment below $442 and $890, respectively, an excessive OOP payment was a barrier to DMT access. This information can inform maximum monthly and yearly payment caps when designing valued-based insurance plans.