What is the definition of febrile neutropenia?

From the Guidelines

Febrile neutropenia is defined as a rise in axillary temperature to above 38.5°C for a duration of >1 h while having an absolute neutrophil count (ANC) of <0.5 · 109/l. This condition is a serious medical emergency that requires prompt attention, as it significantly increases the risk of serious, potentially life-threatening infections due to the body's compromised ability to mount an effective immune response against pathogens. The definition of febrile neutropenia is crucial for identifying patients at risk and initiating appropriate management, including hospitalization, blood cultures, and immediate initiation of broad-spectrum antibiotics 1.

Some key points to consider in the definition and management of febrile neutropenia include:

• The importance of monitoring temperature and ANC levels in patients undergoing chemotherapy or hematopoietic stem-cell transplantation (HSCT) to promptly identify those at risk of febrile neutropenia.
• The need for immediate initiation of broad-spectrum antibiotics in patients with febrile neutropenia, even before culture results are available, due to the high risk of serious infections.
• The consideration of antimicrobial prophylaxis for adult patients with cancer-related immunosuppression, as outlined in clinical practice guidelines 1.
• The potential use of hematopoietic growth factors, such as granulocyte colony-stimulating factor (G-CSF) or its pegylated form (pegfilgrastim), in certain situations, such as primary prophylaxis of febrile neutropenia or treatment of febrile neutropenia with increased morbidity and mortality 1.

Overall, the management of febrile neutropenia requires a comprehensive approach that takes into account the patient's individual risk factors, the severity of their condition, and the latest clinical practice guidelines. The most recent and highest quality study, published in 2018, provides updated guidance on antimicrobial prophylaxis for adult patients with cancer-related immunosuppression, emphasizing the importance of prompt and effective management of febrile neutropenia 1.

From the Research

Definition of Febrile Neutropenia

• Febrile neutropenia (FN) is defined by an absolute neutrophil count (ANC) less than or equal to 500 cells per microliter with a concurrent single oral body temperature of more than or equal to 38.3° C (orally) or more than 38.0° C maintained over one hour 2.
• This condition is associated with mortality rates as high as 40%, highlighting the importance of appropriate clinical management in this patient population 3.
• The definition of febrile neutropenia can also be broad or narrow, with the broad definition including a body temperature above 38°C with an ANC below 0.5 × 10^9/L or a body temperature above 38°C with a diagnosis of neutropenia, and the narrow definition including both fever and neutropenia diagnoses or having both neutropenia and infection diagnoses 4.

Key Characteristics

• Febrile neutropenia is a serious complication that can occur in patients receiving chemotherapy, particularly those with hematological malignancies 5, 6.
• The condition requires prompt empirical antibiotic therapy to reduce the risk of mortality related to infection 5, 6, 3.
• The choice of antibiotic therapy is crucial, with broad-spectrum intravenous bactericidal, anti-pseudomonal antibiotics being accepted treatments for febrile neutropenic patients 5.

Diagnostic Criteria

• The diagnostic criteria for febrile neutropenia include an absolute neutrophil count (ANC) less than or equal to 500 cells per microliter and a concurrent single oral body temperature of more than or equal to 38.3° C (orally) or more than 38.0° C maintained over one hour 2.
• The diagnosis can also be based on the presence of fever and neutropenia, or the presence of neutropenia and infection 4.