What is the definition of neutropenic fever?

Definition of Neutropenic Fever

Neutropenic fever is defined as a single oral temperature of ≥38.3°C (101°F) or a temperature ≥38.0°C (100.4°F) sustained over a 1-hour period, in a patient with an absolute neutrophil count (ANC) <500 cells/mm³ or <1000 cells/mm³ with a predicted decrease to <500 cells/mm³. 1, 2

Temperature Criteria

• Single oral temperature measurement of ≥38.3°C (101°F) 2
• OR temperature ≥38.0°C (100.4°F) sustained for at least 1 hour 2

Neutrophil Count Criteria

• Absolute neutrophil count <500 cells/mm³ (severe neutropenia) 1, 2
• OR neutrophil count <1000 cells/mm³ with a predicted decline to <500 cells/mm³ 2
• Profound neutropenia is defined as ANC <100 cells/mm³ 1
• Protracted neutropenia is defined as neutropenia lasting ≥7 days 1

Clinical Significance

• Neutropenic fever represents a medical emergency requiring urgent evaluation and treatment 2
• Empirical antibiotic therapy should be initiated within 2 hours of presentation 2
• Mortality rates vary significantly: 5% overall in patients with solid tumors, up to 11% in hematological malignancies, and 18% in Gram-negative bacteremia 2
• At least half of neutropenic patients who become febrile have an established or occult infection 2
• At least one-fifth of patients with neutrophil counts <100 cells/mm³ have bacteremia 2

Important Considerations

• Symptoms and signs of inflammation may be minimal or absent in severely neutropenic patients, making fever often the only sign of infection 2
• The duration of neutropenia is a critical risk factor for infection severity, with protracted neutropenia (≥7 days) associated with higher risk 2
• Patients who have received chemotherapy within 6 weeks of presentation are at high risk for neutropenia 3
• Infection can progress rapidly in neutropenic patients, requiring prompt initiation of empirical broad-spectrum antibiotics 2

Common Pitfalls

• Relying on classic signs of infection, which may be absent in neutropenic patients 2
• Delaying antibiotic administration beyond the recommended 1-hour door-to-needle time 4
• Failing to recognize neutropenic fever as an oncologic emergency requiring immediate intervention 3, 5
• Not considering neutropenic fever in patients who have received chemotherapy within the previous 6 weeks 3

Neutropenic fever is a serious condition that requires rapid assessment, diagnosis, and treatment to reduce morbidity and mortality in immunocompromised patients 2, 3.