Comparative effectiveness of colony-stimulating factors for febrile neutropenia: a retrospective study

Abstract

Background:

Granulocyte colony stimulating factors (G-CSFs) decrease the incidence of febrile neutropenia (FN) in cancer patients receiving myelosuppressive chemotherapy. There are two G-CSFs (pegfilgrastim and filgrastim) that differ in dosing schedules from which oncologists may prescribe.

Objectives:

This study aimed to compare the effectiveness of prophylactic pegfilgrastim and filgrastim on the risk of hospitalizations. The secondary objective was to compare the effectiveness of the timing of initiation (prophylactic versus delayed).

Methods:

A retrospective study of administrative claims from US commercial payers included adult patients with Non-Hodgkin’s lymphoma, breast, or lung cancer, treated with chemotherapy between July 2004 and January 2008. For these patients, the first course of chemotherapy and each unique cycle with use of G-CSF was identified and designated ‘prophylaxis’ if used within the first 5 days of each cycle, or ‘delayed’, if after day 5. The risk of neutropenia-related and all-cause hospitalization was evaluated for the pegfilgrastim and filgrastim prophylaxis cohorts and for the prophylaxis and delayed G-CSF initiation cohorts.

Results:

Among 5571 patient-cycles identified, 88.9% and 11.1% used pegfilgrastim and filgrastim respectively. The rate of neutropenic hospitalization was 1.1% for pegfilgrastim prophylaxis and 3.5% for filgrastim prophylaxis (P = 0.001). Compared to chemotherapy cycles with filgrastim prophylaxis, those with pegfilgrastim prophylaxis had decreased risk of neutropenia-related (adjusted odds ratio (OR) = 0.38, 95% confidence interval (CI) 0.17–0.83) and all-cause hospitalization (adjusted OR = 0.51, 95% CI 0.31–0.84). The neutropenic hospitalization rate was 1.2% for G-CSF prophylactic initiation and 3.7% for delayed G-CSF initiation (P < 0.001). Chemotherapy cycles with prophylactic initiation of either G-CSF had decreased risk of neutropenia-related (adjusted OR = 0.34, 95% CI 0.21–0.56) and all-cause hospitalization (adjusted OR = 0.67, 95% CI 0.49–0.91) compared with delayed initiation of G-CSF.

Conclusions:

Pegfilgrastim prescribed as prophylaxis resulted in lower risk of neutropenia-related and all-cause hospitalizations compared to filgrastim prophylaxis. This reduction was similar for prophylactic G-CSF initiation when compared to delayed G-CSF initiation.

Key words::

• Colony-stimulating factors
• Comparative effectiveness
• Febrile neutropenia
• Filgrastim
• G-CSF
• Pegfilgrastim

Transparency

Declaration of funding/support

This study was funded by Amgen.

Declaration of financial/other relationships

H.T. and G.D. have disclosed that they are employees of HealthCore, Inc., a fully owned subsidiary of WellPoint, Inc., which received research funding from Amgen. D.H. and R.B. have disclosed that they are employees of Amgen and own stock and/or stock options in Amgen. J.M. has disclosed that she is a consultant to Amgen. K.T. has disclosed that she was an employee of HealthCore, Inc., at the time the manuscript was written, but is currently employed by Thomson Reuters.

Acknowledgments

The authors thank Seema Sonnad, PhD, University of Pennsylvania, Philadelphia, PA, USA, for her medical writing assistance in the first draft of the manuscript. Concept and design of the manuscript was done by H.T., K.T., G.D., R.B. and J.M. The acquisition of data was done by H.T. and G.D. Analysis and interpretation was done by H.T., K.T., D.H., G.D., R.B. and J.M. Drafting of the manuscript was done by H.T., K.T., D.H. and R.B. Revision of the manuscript was done by H.T., K.T., D.H., G.D., R.B. and J.M. The authors relied upon H.T., K.T. and G.D. for statistical expertise.

Preliminary results from this study were presented at the American Society of Clinical Oncology 2009 Annual Meeting, May 29 – June 2, 2009, Orlando, FL, USA.

Notes

*Neupogen and Neulasta are registered trade names of Amgen Inc., Thousand Oaks, CA.