Neupogen (Filgrastim), Remicade (Infliximab), and Neulasta (Pegfilgrastim) & Biosimilar Use

Following the new regulatory pathway for approval of biosimilar and interchangeable products, FDA needs to be able to evaluate their post-marketing experience. However, how biosimilars are coded for reimbursement, and therefore appear in claims data, is unknown. Since accurate identification of biologics and biosimilars in claims data is a fundamental need for future studies of these products, this study was conducted to examine how patient exposure to biologics and biosimilars can be identified in claims data. Use of filgrastim and infliximab was identified primarily via Healthcare Common Procedure Coding System (HCPCS) codes (filgrastim: 86.4%-97.7%; infliximab: 87.8%-100%) although some use was identified via National Drug Codes (NDCs) (filgrastim: 2.2%-13.5%; infliximab: <0.1%-6.5%). The median exposure episode gap ranged from 1 to 3 days for filgrastim and 48 to 50 days for infliximab. Data on identification of biosimilars in claims data and observed gaps between exposure episodes can be used to support future drug safety studies of biosimilars.