Study Identifies Biosimilar Coverage Trends of Commercial Health Plans

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Coverage restrictions on biosimilars were observed in highly prevalent diseases but were less likely in biosimilars that generate an annual list price savings of more than $15,000 per patient.

Investigators revealed new details of biosimilar coverage according to commercial health plans in the US, specifically relative to the drug’s reference products. The study found that cancer treatments and prevalent conditions within the pediatric population are among the significant factors associated with biosimilar coverage decisions.

Findings displayed coverage restrictions were imposed by health plans on biosimilars in almost 20% of decisions. This was observed in the form of exclusions or step therapy restrictions, compared with reference products.

The investigators noted that biosimilars were introduced to the market with the aim to increase competition with high-priced biologic therapies and to improve efficiency gains. However, the coverage offered by commercial health plans has been limited, and the implementation of biosimilars has been slower than expected.

Assessing Associations with Biosimilar Restrictions

Tianzhou Yu, Department of Pharmaceutical and Health Economics, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, and the team of investigators aimed to explore factors associated with biosimilar coverage relative to their reference products by commercial plans in the US.

A total of 1181 coverage decisions were identified relative to 19 commercially available biosimilars with information from the Tufts Medical Center Specialty Drug Evidence and Coverage database. These matched 7 reference products and 28 indications.

Of the 1181 coverage decisions, data demonstrated that health plans excluded or restricted biosimilars in 229 (19.4%). Aside from the associations of identified restrictions in the pediatric population (odds ratio [OR] 11.558, 95% confidence interval [CI] 3.906-34.203), and in diseases with > 1,000,000 prevalence (OR 2.067, 95% CI 1.060-4.029), results showed pharmacy contracts were also factors.

If the plan didn’t contract with one of the 3 major pharmacy benefit managers the likelihood of higher restrictions was observed (OR 1.683, 95% CI 1.129-2.507), investigators reported.

Factors of Health Plan Decisions

Alternatively, health plans were less likely to impose restrictions on the biosimilar-indication pairs if the biosimilar was indicated for cancer treatments (OR 0.019, 95% CI 0.008-0.041), if the biosimilar was the first biosimilar on the market (OR 0.225, 95% CI 0.118-0.429), and if the biosimilar had 2 competitors (OR 0.060, 95% CI 0.006-0.586).

Additionally, when the biosimilar could yield an annual list price savings of greater than $15,000 per patient (OR 0.171, 95% CI 0.057-0.514), the association with restriction decreased, similarly this pattern was also present when the reference product was restricted by the plan (OR 0.065, 95% CI 0.038-0.109), or if a cost-effectiveness measure was not available (OR 0.066, 95% CI 0.023-0.186).

When examining the cost-effectiveness of the drugs, data was utilized from Tufts Medical Center Cost-Effectiveness Analysis Registry, and the Merative Micromedex RED BOOK provided the list prices.

A multivariate logistic regression was employed to examine the association between coverage restrictiveness and a number of potential drivers of coverage.


  1. Yu T, Jin S, Li C, Chambers JD, Hlávka JP. Factors Associated with Biosimilar Exclusions and Step Therapy Restrictions Among US Commercial Health Plans [published online ahead of print, 2023 Apr 1]. BioDrugs. 2023;10.1007/s40259-023-00593-7. doi:10.1007/s40259-023-00593-7