Pegfilgrastim prophylaxis is associated with a lower risk of hospitalization of cancer patients than filgrastim prophylaxis: a retrospective United States claims analysis of granulocyte colony-stimulating factors (G-CSF)

Abstract

Background: Myelosuppressive chemotherapy can lead to dose-limiting febrile neutropenia. Prophylactic use of recombinant human G-CSF such as daily filgrastim and once-per-cycle pegfilgrastim may reduce the incidence of febrile neutropenia. This comparative study examined the effect of pegfilgrastim versus daily filgrastim on the risk of hospitalization.

Methods: This retrospective United States claims analysis utilized 2004-2009 data for filgrastim- and pegfilgrastim-treated patients receiving chemotherapy for non-Hodgkin's lymphoma (NHL) or breast, lung, ovarian, or colorectal cancers. Cycles in which pegfilgrastim or filgrastim was administered within 5 days from initiation of chemotherapy (considered to represent prophylaxis) were pooled for analysis. Neutropenia-related hospitalization and other healthcare encounters were defined with a "narrow" criterion for claims with an ICD-9 code for neutropenia and with a "broad" criterion for claims with an ICD-9 code for neutropenia, fever, or infection. Odds ratios (OR) for hospitalization and 95% confidence intervals (CI) were estimated by generalized estimating equation (GEE) models and adjusted for patient, tumor, and treatment characteristics. Per-cycle healthcare utilization and costs were examined for cycles with pegfilgrastim or filgrastim prophylaxis.

Results: We identified 3,535 patients receiving G-CSF prophylaxis, representing 12,056 chemotherapy cycles (11,683 pegfilgrastim, 373 filgrastim). The mean duration of filgrastim prophylaxis in the sample was 4.8 days. The mean duration of pegfilgrastim prophylaxis in the sample was 1.0 day, consistent with the recommended dosage of pegfilgrastim - a single injection once per chemotherapy cycle. Cycles with prophylactic pegfilgrastim were associated with a decreased risk of neutropenia-related hospitalization (narrow definition: OR = 0.43, 95% CI: 0.16-1.13; broad definition: OR = 0.38, 95% CI: 0.24-0.59) and all-cause hospitalization (OR = 0.50, 95% CI: 0.35-0.72) versus cycles with prophylactic filgrastim. For neutropenia-related utilization by setting of care, there were more ambulatory visits and hospitalizations per cycle associated with filgrastim prophylaxis than with pegfilgrastim prophylaxis. Mean per-cycle neutropenia-related costs were also higher with prophylactic filgrastim than with prophylactic pegfilgrastim.

Conclusions: In this comparative effectiveness study, pegfilgrastim prophylaxis was associated with a reduced risk of neutropenia-related or all-cause hospitalization relative to filgrastim prophylaxis.

Figure 1

Odds ratios for neutropenia-related and all-cause hospitalization regarding prophylactic pegfilgrastim versus prophylactic filgrastim. Odds ratios (ORs) and 95% confidence intervals (95% CI) for hospitalization are shown with pegfilgrastim versus filgrastim prophylaxis, adjusted for patient, cancer, and chemotherapy characteristics. The primary analysis included all cycles in which G-CSF was used prophylactically. The subgroup analysis only included those cycles in which patients received 4 or more days of filgrastim (as described in the Methods section under “Sensitivity Analyses”).

Figure 2

Costs per cycle: All-cause and neutropenia-related. Healthcare resource costs, for cycles in which pegfilgrastim and filgrastim were used prophylactically, were calculated on a per-cycle basis to provide total costs as well as subgroup costs by setting of care: ambulatory care, emergency room, and hospitalizations. The costs were direct costs for services covered under patients’ insurance benefits and represented the reimbursed amount paid by the patient and insurer.