Risk and Consequences of Neutropenic Complications Among Patients with Metastatic Solid Tumors Receiving Myelosuppressive Chemotherapy

While several studies have evaluated the risk and consequences of febrile neutropenia (FN) among patients receiving cancer chemotherapy in US clinical practice, none have focused on a broad group of patients with metastatic disease.

A retrospective cohort design and US healthcare claims data (2007-2011) were utilized. Study population included adult patients who underwent myelosuppressive chemotherapy for metastatic cancer of the breast (MBC), colon/rectum (MCC), lung (MLC), ovaries (MOC), or prostate (MPC). For each subject, the first qualifying chemotherapy course and each chemotherapy cycle therein, and each episode of chemotherapy-induced neutropenic complications (CINC) during the course, were identified; use of prophylaxis with colony-stimulating factors (CSF) and oral antimicrobial (AMB) agents also was identified. CINC was ascertained using broad (diagnosis of neutropenia, fever, and/or infection) and narrow (diagnosis of neutropenia) definitions, and was stratified by care setting. (Our outcome was CINC, rather than FN, because clinical data were not available and there is no specific diagnosis code for FN. In a validation study, FN risk was reported to be between risk of CINC based alternatively on aforementioned broad and narrow criteria [Weycker, BMC Health Services Research 2013].) Risk (i.e., incidence proportion) of CINC was estimated by tumor type and regimen; consequences of CINC-hospital length of stay (LOS) and mortality, CINC-related healthcare costs-were estimated by tumor type.

CINC risk is reported herein only for the most frequently observed regimen for each tumor type: paclitaxel for MBC (17.8% of 15,309 patients), 5-fluorouracil + leucovorin + oxaliplatin for MCC (23.4% of 16,934), carboplatin + paclitaxel for MLC (22.9% of 21,994), carboplatin + paclitaxel for MOC (49.2% of 7,435), and docetaxel for MPC (68.4% of 4,668). Across these 5 regimens, use of CSF prophylaxis in cycle 1 ranged from 4.6-24.6% (Table 1). Risk of CINC (broad definition) during the course ranged from 11.6-20.5%; among subjects with CINC, 87.7-95.3% had CINC in the inpatient setting and 16.8-33.8% had CINC in cycle 1. For CINC requiring inpatient care (broad definition), hospital mortality ranged from 4.4-9.8%, hospital LOS (mean) from 6.9-7.3 days, and healthcare costs (mean) from $12,831-$16,003 across tumor types (Table 2). CINC risks based on narrow definition are in Table 1; CINC consequences based on narrow definition were similar to those for broad definition.

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Among patients receiving common myelosuppressive chemotherapy regimens for metastatic disease in solid tumors in US clinical practice, 4.6-24.6% were administered CSF prophylaxis in cycle 1, while 11.6-20.5% experienced CINC (broad definition), treated most often in the inpatient setting.

Weycker:Amgen Inc.: Research Funding. Li:Amgen Inc.: Employment, Equity Ownership. Kartashov:Amgen Inc.: Research Funding. Barron:Amgen Inc.: Employment, Equity Ownership. Edelsberg:Amgen Inc.: Research Funding. Xu:Amgen Inc.: Employment, Equity Ownership. Girardi:Amgen Inc.: Employment, Equity Ownership. Lyman:Amgen Inc.: PI on a research grant to Duke University Other.