Impact of primary prophylactic colony stimulating factor delivery method on febrile neutropenia.

36 Background: Primary prophylactic colony stimulating factor (PP-CSF) is recommended for patients at high risk of febrile neutropenia (FN) receiving chemotherapy. Delivery options for PP-CSF include in-clinic administration (IC), home delivery via an on-body device (OBD), or home self-injection without a device (SI). OBDs are marketed as more convenient and as potentially improving adherence, but are associated with higher costs. The impact of PP-CSF delivery method on FN risk is unknown. SWOG S1415CD (TrACER) was a pragmatic, cluster-randomized trial evaluating a guideline informed standing order system to improve PP-CSF use and reduce FN. We conducted a secondary analysis of TrACER to evaluate associations between PP-CSF delivery method and FN. Methods: Female patients with breast cancer enrolled in TrACER who received PP-CSF with a known delivery method were included. The primary outcome was FN within 6 months by delivery method (IC, OBD, SI). Multivariable logistic regression adjusted for delivery method, PP-CSF agent, FN risk category of the chemotherapy regimen, and performance status (PS). Secondary outcomes included adherence to chemotherapy and PP-CSF. Results: Of 1713 patients, 773 (45%) received IC, 862 (50%) received OBD, and 78 (5%) received SI. Most received high-risk FN chemotherapy regimens (IC 86%, OBD 87%, SI 91%). Patients in the IC and OBD groups received pegfilgrastim almost exclusively (98% and 99%, respectively), compared to 29% in the SI group. IC patients were more likely to receive PP-CSF on the same day as chemotherapy rather than the recommended next-day administration (p < 0.001). IC and OBD groups were demographically similar (white 86% and 82%; Medicaid 12% and 9%) while the SI group was more diverse (white 56%, Medicaid 40%). FN incidence was low: IC 3.8% (95% CI 2.5–5.3%), OBD 5.0% (3.6–6.6%), SI 6.4% (2.1–14.3%) (p = 0.29). In multivariable analysis, FN was associated with high-risk FN chemotherapy regimens (OR 2.97, 95% CI 1.2–9.9, p = 0.038) and PS ≥2 (OR 4.99, 95% CI 1.12–15.9, p = 0.014); neither delivery method nor PP-CSF agent was significantly associated with FN. Chemotherapy adherence (dose intensity and duration) did not differ by delivery method. Conclusions: FN rates were low across all PP-CSF delivery methods. There were no significant differences in FN based on PP-CSF delivery method or agent. Given the similar outcomes, delivery decisions may be guided by patient-centered factors such as cost, convenience, and access. These findings may inform future prescribing practices and payer coverage policies. Clinical trial information: NCT02728596 .