Low-Flexibility Insurance Plans More Likely to Prescribe Biosimilars


Results revealed the health plan type highly influenced the likelihood of biosimilar uptake, with low-flexibility insurance plans more likely to have patients who either switched to a biosimilar or were initiated on a biosimilar.

Low-Flexibility Insurance Plans More Likely to Prescribe Biosimilars

Jeremy Costin, MHS

Credit: LinkedIn

Patients with low-flexibility plans, such as Exclusive Provider Organization (EPOs) and Health Maintenance Organization (HMOs), were more likely to include patients who were initiated on biosimilars or switched to a biosimilar, according to a study published in Springer Link.1

“Understanding the full scope of how health plan type influences the use of biologics and biosimilars is crucial for policymakers and healthcare stakeholders as they work toward increasing biosimilar uptake and lowering drug spending for biological therapies,” wrote a team of investigators led by Jeremy Costin, MHS, associated with the Department of International Health, Johns Hopkins Bloomberg School of Public Health.

Although biosimilars may lower drug costs for biological treatment, most biosimilars available in the US do not have an interchangeable designation and may not be prescribed in place of the reference drug without a new prescription. Therefore, the adoption of biosimilars depends predominantly on the physician’s discretion as well as the incorporation of the biosimilar into the drug formularies of health insurance plans.2

Investigators analyzed the role of health insurance plans on biosimilar adoption among commercially insured patients in the US using IBM MarketScan Commercial Claims and Encounters (CCAE) data from 2015 to 2019. Switchers and biosimilar initiators were evaluated for 6 biologic–biosimilar pairs. It was hypothesized plans with different levels of flexibility may exhibit different biosimilar coverage because of cost considerations, provider networks, and formulary design. Sequential regression models were used to assess this link and linear probability models controlled for patient demographics and drug group.

Results revealed the health plan type highly influenced the likelihood of biosimilar uptake. Specifically, plans with lower flexibility were more likely to have patients who either switched to a biosimilar or were initiated on a biosimilar. Compared with high-deductible plans, patients in a high-flexibility plan were less likely to switch and/or initiate biosimilar treatment.

When compared with patients in high-deductible plans, the probability of being a switcher was 1% higher for those in a low-flexibility plan (P < .01). Additionally, the likelihood of being an initiator was 2% higher (P <.01). These results represent a 33% increase in the probability of switching to a biosimilar in this type of health plan.

Conversely, enrollment in a high-flexibility plan was linked to a .9% lower probability of being a switcher (P <.01) and a 1% lower probability of being an initiator (P <. 01) compared with high-deductible plans. Therefore, low-flexibility insurance plans may be a more effective strategy for encouraging biosimilar uptake.

Investigators noted the study was limited by evaluating pharmacy claims data, which only included medication data collected through pharmacy benefit. Therefore, future studies should focus on biologics and biosimilars prescribed in the outpatient setting to better understand the factors driving product selection. Additionally, the study was unable to fully explore why different plan types reported different rates of biosimilar adoption as the dataset did not provide information on rebates.

“As biosimilars gain interchangeability approval, it remains a policy challenge for policymakers and researchers to promote biosimilar adoption,” investigators concluded. “In this context, it may be worthwhile to investigate the practices of HMOs and EPOs, which seem to be associated with increased biosimilar switching and initiation. Such research can provide insights into the factors that influence the uptake of biosimilars and help identify strategies to further promote their use.”


  1. Costin J, Mouslim MC, Socal MP, Trujillo A. Exploring the Influence of Health Insurance Plans on Biosimilar Adoption Rates [published online ahead of print, 2023 Nov 3]. Pharmacoecon Open. 2023;10.1007/s41669-023-00447-6. doi:10.1007/s41669-023-00447-6
  2. Teeple A, Ginsburg S, Howard L, et al. Patient attitudes about non-medical switching to biosimilars: results from an online patient survey in the United States. Curr Med Res Opin. 2019;35(4):603–9. https://doi.org/10.1080/03007995.2018.1560221.
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