Physicians have been slow to embrace biosimilar versions of infliximab, but are more likely to prescribe it to new patients, based on data from a review of nearly 50,000 infliximab claims through Medicare in the first 2 years that biosimilars were available in the United States.
“Although biosimilar versions are as safe and effective as the biologic, patients and physicians may be more reluctant to switch from a working biologic regimen in a chronic setting than an acute one,” wrote Alice J. Chen, PhD, of the University of Southern California, Los Angeles, and colleagues.
In a research letter published in JAMA Internal Medicine, the investigators examined prescribing patterns of physicians switching between the originator infliximab (Remicade) and two of its biosimilars (Inflectra and Renflexis).
They reviewed infliximab use and reimbursement in the 100% Medicare Part B quarterly claims database from Jan. 1, 2017, to Dec. 31, 2018. The study population included Medicare patients classified as new if they had no infliximab claims in the prior 6 months; those with claims were considered returning patients.
In a comparison of claims reflecting 49,771 patients and 4,289 physicians in 2018, a total of 1,418 new patients (17.4%) and 4,495 (10.8%) returning patients used a biosimilar. “Of returning patients, half used the biosimilar version exclusively, whereas the other half switched between biologic and biosimilar versions,” the researchers noted.
Of the 4,289 physicians who prescribed infliximab, 3,124 prescribed no biosimilars, 1,015 prescribed both biologics and biosimilars, and 150 prescribed biosimilars only. Of the physicians who prescribed both, approximately 61% switched some patients from the biologic to the biosimilar; “the remainder kept individual patients on only 1 version of the drug but treated patients with both versions,” the researchers wrote.
The adoption of biosimilars may be slower for chronic vs. acute conditions, the researchers noted. “Prescribers may hesitate to switch clinically stable chronic patients from biologic regimens if they are unfamiliar with the biosimilar or face financial disincentives from prescribing it.”
The study findings were limited by several factors including the use of only 2 years of data and a focus only on Medicare Part B. Switching medications may have been influenced by factors such as lower copays for patients and rebates or discounts for physicians; however, “further research is needed to better understand biosimilar pricing dynamics and the barriers to adopting biosimilars for chronic conditions,” they concluded.
The study was supported by the Leonard D. Schaeffer Center for Health Policy & Economics at the University of Southern California, Los Angeles, and the National Institute on Aging. Lead author Dr. Chen also disclosed receiving personal fees from Amgen outside of the current study.
SOURCE: Chen AJ et al. JAMA Intern Med. 2020 July 20. doi: 10.1001/jamainternmed.2020.3188.