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Zarxio Uptake Earlier, Faster in Office Settings, Study Says


A new study found that office-based providers, especially those with large practice sizes, were earlier and quicker at adopting biosimilar filgrastim (Zarxio) than hospital-based providers.

Office-based providers, especially those with large practice sizes, were found to be earlier and quicker adopters of biosimilar filgrastim (Zarxio) than hospital-based providers, according to a new study published in The American Journal of Managed Care (AJMC®).

Study results showed that the share of biosimilar filgrastim claims rose to 60% among office-based providers after 3 years on the market. During the same amount of time, biosimilar filgrastim claims rose to 49% among providers at outpatient hospitals.

Hospital Margins May Control Uptake

One reason for this is that, “Compared with office-based providers, hospital-based providers are more likely to be reimbursed as a percentage of hospital charges, where the charges are set by the hospitals themselves and include significant profit margins on physician-administered drugs,” the authors noted.

Across all healthcare settings, providers typically chose either the reference biologic (Neupogen) or the biosimilar to prescribe, and very few offered both as options.

“This pattern suggests that, at least within a provider group, patients were unlikely to have been presented with the option to choose between the biologic and the biosimilar, which highlights the importance of the provider’s role in biosimilar adoption,” the authors said.

On average, 18% of all providers’ filgrastim claims were associated with health management organization (HMO) contacts. For practices providing some Zarxio, HMO contracts were associated with 22% of claims. That dropped to 14% for those providing only Neupogen, suggesting that HMOs may be associated with increased biosimilar uptake.

Patient Profile

The average patient receiving filgrastim was 70 years old, with 22% being nonwhite and 42% being men. Patient populations differed between providers of only Neupogen and those who also prescribed the biosimilar. The latter group had a higher share of nonwhite patients (increase of 4.9 percentage points), slightly more males (increase of 1.8 percentage points), and younger patients on average (by 2 years).

“Providers with patients who might be more burdened by the costs of care, such as younger patients who do not meet the age-eligibility requirement for Medicare coverage or nonwhite patients of likely lower socioeconomic status, were more likely to use the biosimilar,” the authors noted.

Authors of a recent study from Canada concluded that, wherever biosimilars are available, adoption rates may be poor without concurrent education and clear understanding of the clinical environments in which these agents would be prescribed.

For the full study, visit ajmc.com.


Chen AJ, Ribero R, Van Nuys K. Provider differences in biosimilar uptake in the filgrastim market [published online March 26, 2020]. Am J Manag Care.

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