Days of Prophylactic Filgrastim Use to Reduce Febrile Neutropenia in Patients

BACKGROUND: Filgrastim prophylaxis lessens the occurrence of febrile neutropenia in patients with non-Hodgkin.s lymphoma (NHL) treated with chemotherapy, but differences in days of therapy and mode (primary or secondary) of prophylaxis may affect clinical outcomes. OBJECTIVE: To describe the patterns of use of filgrastim prophylaxis, especially days of therapy and mode, and the possible associated incidence of febrile neutropenia in patients treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy. METHODS: Using medical records from the Oncology Practice Pattern Study in patients treated between 1991 and 1999 at 12 sites in the United States, we studied patients with intermediate-grade NHL treated with first-line CHOP chemotherapy and prophylactic filgrastim. The number of days of prophylactic filgrastim use, mode of prophylaxis, and incidence of febrile neutropenia were evaluated. The cycles were stratified into 2 groups based on days of filgrastim prophylaxis ( or = 7 days Group 2). RESULTS: One hundred seventy patients were treated with 652 cycles of CHOP chemotherapy with filgrastim prophylaxis. The mean days of filgrastim prophylaxis was 9.5 days (95% confidence interval CI, 9.3-9.7 days) across all cycles, 4.7 days (95% CI, 4.5-5.0 days) across Group 1 cycles (n=73), and 10.1 days (95% CI, 9.9-10.3 days) across Group 2 cycles (n=579). Thirty-seven percent of patients were treated with primary prophylaxis; 94% of these patients. cycles were Group 2 cycles. The incidence of febrile neutropenia was 3.6% and 7.7% across cycles in patients receiving primary versus secondary prophylaxis, respectively. In patients treated with secondary prophylaxis, the incidence was 16.7% and 6.1% in Group 1 and Group 2 cycles, respectively. Multiple logistic regression modeling indicated that a lower risk of febrile neutropenia was associated with primary prophylaxis (mainly Group 2) (odds ratio OR 0.3; 95% CI, 0.1-0.6) and secondary prophylaxis in Group 2 (OR 0.4; 95% CI, 0.2-0.8), and lower body surface area was associated with a greater risk of febrile neutropenia (OR 1.8; 95% CI, 1.1-3.0). CONCLUSION: Primary prophylaxis with filgrastim (mainly Group 2) and secondary prophylaxis in Group 2 (mean 10.1 days) may be associated with a lower incidence of febrile neutropenia than secondary prophylaxis in Group 1.