Provider Differences in Biosimilar Uptake in the Filgrastim Market

OBJECTIVES: To identify differences in biosimilar uptake across providers and to examine the association between provider biosimilar uptake and observable practice-level characteristics. STUDY DESIGN: A retrospective analysis of 100% of a commercial medical claims database from June 2015 to June 2018. METHODS: We focused on providers of biologic (Neupogen) and biosimilar (Zarxio) filgrastim. We compared trends in biosimilar uptake across 2 dimensions: provider's place of service and provider's prescribing exclusivity. We then used multivariate regression analysis to estimate the association between any biosimilar uptake and practice-level characteristics, controlling for geography and time fixed effects. RESULTS: Relative to hospital-based providers, office-based providers were earlier and quicker adopters of the biosimilar filgrastim. Across all places of service, providers predominantly prescribed either the biosimilar or biologic, exclusively, for all their patients. Any biosimilar uptake was more common among providers in office-based settings, providers with larger practice sizes, and providers with a higher share of health maintenance organization patients, nonwhite patients, and younger patients. CONCLUSIONS: This study uncovers important associations between provider practice characteristics and biosimilar uptake. Our findings suggest that provider awareness and incentives can be important levers to strengthen US biosimilar market penetration and competition.