This comparative effectiveness and descriptive retrospective cohort study includes commercially insured adults enrolled in one of four health plans participating in the Biologics and Biosimilars Collective Intelligence Consortium (BBCIC) Distributed Research Network. The investigators included patients who received a granulocyte colony stimulating factor (G-CSF) biosimilar or originator product during the first cycle of clinical guideline-indicated intermediate or high febrile neutropenia risk chemotherapy. The investigators will collect patient demographics, cancer diagnosis, chemotherapy regimen, and patterns of G-CSF biosimilar and originator product use. The investigators will follow patients from first G-CSF exposure until up to six cycles of chemotherapy receipt, death, or insurance disenrollment. The primary effectiveness outcome is incidence of febrile neutropenia. Secondary outcomes include incidence of adverse events and trends in product use over time. The investigators will compare febrile neutropenia incidence between originator and biosimilar products using inverse probability weighting to control for confounding. Secondary analyses will examine 'as treated' outcomes.
