Risk of Infection Among Patients with Non-Metastatic Solid Tumors or Non-Hodgkin’s Lymphoma Receiving Myelosuppressive Chemotherapy and Antimicrobial Prophylaxis in US Clinical Practice

Clinical practice guidelines recommend oral antimicrobials (AMB)—principally, the fluoroquinolones—for prophylaxis against chemotherapy-related infections (CRI) in intermediate- and high-risk patients undergoing myelosuppressive chemotherapy. Available evidence on the risk of CRI among patients with non-metastatic solid tumors or non-Hodgkin's lymphoma (NHL) receiving myelosuppressive chemotherapy and AMB prophylaxis in US clinical practice is currently limited.

A retrospective cohort design and data from two US private healthcare claims repositories (2008-2011) were employed. The study population included adult patients who received myelosuppressive chemotherapy for non-metastatic cancer of the breast, colon/rectum, or lung, or for NHL. For each study subject, the first qualifying chemotherapy course, and each chemotherapy cycle and episode of CRI within the course, were identified. Use of prophylaxis with oral AMB agents—including antibacterial, antifungal, and antiviral drugs—as well as colony-stimulating factors (CSF) in each cycle also was identified. CRI was ascertained based on admission to an acute-care inpatient facility with a corresponding diagnosis (1⁰ or 2⁰) or an ambulatory encounter with a corresponding diagnosis and evidence of AMB therapy. Risk of CRI was evaluated during chemotherapy cycles in which patients received AMB prophylaxis; only results for the most frequently observed regimen for each tumor type are reported herein.

The most common regimens—by tumor—were: breast cancer, docetaxel + cyclophosphamide (“TC”, 29% of 34,876); colorectal cancer, folinic acid (leucovorin) + fluorouracil + oxaliplatin (“FOLFOX”, 34% of 14,334); lung cancer, paclitaxel + carboplatin (“PC”, 25% of 17,334); and NHL, cyclophosphamide + doxorubicin + vincristine + prednisone with Rituxan (“CHOP-R”, 45% of 9,612). Across these four regimens, use of AMB prophylaxis in cycle 1 ranged from 3.5-8.6%; fluoroquinolones were the most common agents administered (range, 27.1-43.5%) (Table 1). Use of CSF prophylaxis in cycle 1 ranged from 10.4-61.2%. Among subjects who received first-cycle AMB prophylaxis, risk of CRI in that cycle ranged from 1.2-7.5%; among these subjects, 45-68% had CRI in the inpatient setting (Table 2). CRI risks in subsequent cycles with AMB prophylaxis were generally comparable.

Among patients with non-metastatic solid tumors or NHL receiving common myelosuppressive chemotherapy and AMB prophylaxis in US clinical practice, risk of CRI ranged from 1.2-8.6% in cycles in which AMB prophylaxis was administered.

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