Objectives: To describe the uptake and out-of-pocket (OOP) costs of Basaglar, the first long-acting insulin biosimilar, in a commercially insured population in the United States.
Study design: Retrospective analysis of commercial pharmacy claims and pharmacy co-payment offsets.
Methods: We assessed Basaglar uptake by examining trends in the composition of the long-acting insulin market in the United States from 2014 to 2018. As patient demographics and plan type may be important determinants of biosimilar uptake, we also assessed characteristics of all long-acting insulin users by drug. We examined Basaglar OOP costs by assessing mean OOP costs per claim for users of Basaglar and other long-acting insulins, overall and by plan type, and the number and source of co-payment offsets for Basaglar and other insulin glargine products from Basaglar market entry through 2018. We used multivariate linear models to examine the relationship between Basaglar OOP expenditures and insurer-negotiated amounts, overall and by plan type.
Results: Basaglar experienced a rapid uptake. However, there was no evidence that Basaglar users had lower OOP costs than reference product (Lantus) users.
Conclusions: Given our results and the approval of the first interchangeable biosimilar, we recommend the empirical evaluation of biosimilar cost savings to patients and insurers prior to promoting their automatic substitution.