Impact of primary prophylaxis on febrile neutropenia within community practices in the US

Objective: To determine if granulocyte-colony-stimulating factor (G-CSF) primary prophylaxis is associated with a lower risk of febrile neutropenia (FN) than non-primary prophylaxis. Methods: This was a retrospective, cohort study of medical records from a random sample of patients with solid tumours and lymphomas treated in 99 community oncology practices in 2003 (n=5319). Consecutively-sampled patients treated with chemotherapy and either filgrastim (Neupogen*), pegfilgrastim (Neulasta^†) or no G-CSF were included (n=3123). Multivariate logistic regression estimated the odds of FN in patients receiving G-CSF primary prophylaxis (within 3 days of first chemotherapy cycle) compared with non-primary prophylaxis (delayed or no G-CSF). Results: Patients receiving primary prophylaxis were less likely to develop FN than patients receiving non-primary prophylaxis (OR=0.49, 95% CI 0.34-0.71, p<0.001). Chemotherapy characteristics were associated with development of FN including, receipt of at least three chemotherapy drugs versus one (OR=2.13, 95% CI 1.17-3.89, p=0.014) and regimens with at least one myelosuppressive drug (OR=2.37, 95% CI 1.19-4.73, p=0.014). Conclusion: Patients receiving G-CSF primary prophylaxis had significantly lower odds of developing FN than those receiving non-primary prophylaxis. Incidence of FN may be underestimated, as care not recorded in the medical oncologist's chart was not captured.