Understanding utilization patterns of biologics and biosimilars in the United States to support postmarketing studies of safety and effectiveness

Purpose To describe utilization of filgrastim and infliximab, the first two products with biosimilars approved in the United States. Methods We identified use of filgrastim (reference, tbo‐filgrastim, and filgrastim‐sndz) and infliximab (reference, infliximab‐dyyb, and infliximab‐abda) in the Sentinel Distributed Database using Healthcare Common Procedure Coding System (HCPCS) codes and National Drug Codes (NDCs) from January 2015 to August 2018. We calculated the proportion of use by code type and assessed uptake over time. We compared baseline patient characteristics and treatment indications. Among patients with >1 exposure episode, we characterized gaps between episodes. Results Use was identified primarily via HCPCS codes (filgrastim: 86.4%‐97.7%; infliximab: 87.8%‐100%) although some was identified via NDCs (filgrastim: 2.2%‐13.5%; infliximab: