Background: The uptake of granulocyte colony stimulating factor (G-CSF) biosimilars has started in clinical practice, but limited comparative research exists on safety and effectiveness in real-world settings.
Objectives: To conduct a scoping review to examine exposure and outcome definitions used in observational studies of long and short-acting G-CSFs. Our findings will inform the design of future comparative effectiveness research (CER) with G-CSF products, including biosimilars.
Methods: Our review identified observational studies of G-CSF use in patients with cancer age 18y+, who received myelosuppressive chemotherapy. We included studies in humans, published in English between January 1, 2012 and December 31, 2019 in Medline. This time period was selected to include study populations from 2011 and beyond to allow for adoption of the 2010 European Organization for Research and Treatment of Cancer (EORTC) clinical practice guidelines. We describe definitions, algorithms and analytic methods used in studies to determine and analyze G-CSF prophylaxis, neutropenia, and healthcare utilization.
Results: The initial search strategy identified 385 studies for title review. After reviewing the abstracts of 136 studies, excluding non-observational studies and those outside our timeframe of interest, we included 13 studies in this review. Of included studies, five were conducted in the U.S., four in Europe, two in multiple countries, one in Canada and one in China. Eight (61%) studies were retrospective, using insurance claims or electronic health records and five (39%) were prospective. Studies evaluated solid tumors (38%), non-Hodgkin’s lymphoma (8%), or a combination of solid and hematologic malignancies (54%). Definition of G-CSF prophylaxis administration varied between 1 and 7 days after initial chemotherapy receipt. Comparators to G-CSF administration included no G-CSF receipt, biosimilar G-CSF product, or G-CSF receipt outside the study definition of prophylaxis. Studies varied in the definition of neutropenia, e.g. with or without fever, with or without other signs of infection. The most common healthcare utilization evaluated was inpatient hospitalization for neutropenia. No studies reported patient-related quality of life.
Conclusions: To allow for comparisons across studies, future CER should use standardized definitions for primary G-CSF prophylaxis receipt and for neutropenia-related outcomes. Future observational research is needed to evaluate patient quality of life.