US Rheumatologists Understand and Accept Biosimilars, but Some Hesitation Remains

Deana Ferreri, PhD

US rheumatologists who prescribe tumor necrosis factor (TNF) inhibitors are familiar with biosimilars; however, there is broad awareness only of infliximab biosimilars, according to a survey. The results suggest most are willing to prescribe a biosimilar for a biologic-naïve patient who has the condition the biosimilar’s approval was based on, but they are hesitant about extrapolated conditions and nonmedical switching.

The authors cited previous research suggesting “health-care providers in the USA and Europe remain cautious” about using biosimilars, and aimed to update the literature with current perceptions of US rheumatologists who prescribe TNF inhibitors.

The 19-question online survey was given to 320 board-certified rheumatologists in the United States. The authors thought it important to gauge the perceptions of rheumatologists because TNF inhibitors “are the cornerstones of therapy for many chronic immune-mediated diseases, such as [rheumatoid arthritis],” and “[rheumatologists] will require education about the biosimilars of these agents before they are comfortable offering them to their patients.”

Survey questions covered rheumatologists’ familiarity with biosimilars, reasons for choosing a biosimilar or its reference product, interchangeability and extrapolation, non-medical switching, and use of biosimilars in different patient scenarios. The survey was administered in May and June of 2019.

Low Awareness of All FDA-Approved Biosimilars

Most rheumatologists (85%) were familiar with the FDA definition of a biosimilar product, but their awareness of FDA-approved biosimilars was “lacking,” according to the authors. Whereas nearly all survey respondents (96%) knew the FDA had approved an infliximab biosimilar, “fewer realized that adalimumab, etanercept and rituximab biosimilars were FDA approved (56%, 62% and 39%, respectively).”

Deciding Between a Biosimilar and Its Reference

Respondents were asked to rank by importance 7 factors they might consider when choosing to prescribe a biosimilar or its reference product: effectiveness, safety, patient cost, immunogenic risk, availability of data on switching, physicochemical and functional characteristics, and durability of response. Effectiveness was ranked first or second by 77% of respondents, followed by safety by 45%, whereas 51% ranked physicochemical and functional characteristics sixth or seventh.

Notably, only 27% of rheumatologists surveyed ranked reduced cost for the patient first or second. Previous research, in contrast, found cost is a significant issue for rheumatologists, but they considered the savings with biosimilars insufficient to prescribe them in place of their reference products.

Prescribing Biosimilars for Extrapolated Conditions

Only about half (54%) of rheumatologists surveyed were familiar with the term “non-medical switching.” When asked about prescribing for a patient with the same condition the biosimilar’s approval was based on, 73% said they were likely to prescribe a biosimilar to a biologic-naïve patient, but only 35% said they were likely to switch a patient who was doing well on the reference product. For an extrapolated condition, rheumatologists were less willing to use biosimilars: 40% rated themselves as likely to prescribe a biosimilar for a biologic-naïve patient, compared with 21% if the patient was doing well on the reference product.

Most (84%) respondents knew that FDA approval does not imply interchangeability, and “86% felt it important/very important for interchangeable approval to be on the label.”

The authors said their results suggest that US rheumatologists “understand and accept” biosimilars, especially for biologic-naïve patients, but they are cautious about extrapolated conditions and non-medical switching. The authors concluded by arguing that “additional education on biosimilars is required to help inform treatment decisions by rheumatologists.”


Gibofsky A, McCabe D. US rheumatologists' beliefs and knowledge about biosimilars: a survey. Rheumatology (Oxford). Published online November 4, 2020. doi:10.1093/rheumatology/keaa502