Background Biosimilars account for 30-40% of biologic medications dispensed in the United States (US), yet healthcare providers in relevant medical specialties have limited awareness of biosimilars and their characteristics. Likewise, many providers perceive biosimilars as less safe and effective than original biologics and are more comfortable prescribing original biologics to patients. Methods We conducted in-person focus groups at three clinical sites in California and Texas (n = 49) to explore the reasons behind US healthcare providers' limited understanding of, cautious attitudes toward, and reluctance to prescribe biosimilars. We conducted thematic analysis by having three researchers independently analyze verbatim transcripts and identify patterns in provider responses. Results Providers' limited knowledge of and cautious attitudes toward biosimilars are driven by uncertainty about how biosimilarity is defined and operationalized as well as negative past experiences with generic drugs that did not perform as well as branded counterparts. Additionally, healthcare providers are unfamiliar with the Food and Drug Administration's (FDA's) approval pathway for biosimilars and are skeptical that an abbreviated approval process is rigorous enough to ensure biosimilars deliver the same efficacy and have the same side effect profiles as original biologics. Physicians also expressed concerns about pharmacy substitution of biosimilars and interchangeables, explaining they would be unaware of which medication was ultimately given to their patients. Conclusions Educating physicians and pharmacists about biosimilars-including how biosimilarity is defined and operationalized, the structure of the biosimilar approval process, and how analytical data can ensure biosimilar safety and efficacy-will be important for reducing healthcare providers' concerns and increasing biosimilar adoption in the US.
