Neutropenic Fever Definition and Management

Temperature and Neutrophil Count Criteria

The Infectious Diseases Society of America defines neutropenic fever as an oral temperature >38.3°C (101°F) as a single measurement or ≥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
Single oral temperature measurement of >38.3°C (101°F) is a criterion for neutropenic fever 1, 2
Temperature ≥38.0°C (100.4°F) sustained for at least 1 hour is also a criterion for neutropenic fever 1, 2
Absolute neutrophil count <500 cells/mm³ is a criterion for neutropenia 3, 4, 5
Neutrophil count <1000 cells/mm³ with a predicted decline to <500 cells/mm³ is also a criterion for neutropenia 6, 7

Neutropenic fever represents a medical emergency requiring urgent evaluation and treatment, with empirical antibiotic therapy initiated within 2 hours of presentation 2
Mortality rates vary significantly, with 5% overall in patients with solid tumors, up to 11% in some hematological malignancies, and 18% in Gram-negative bacteremia 3, 4
Mortality correlates with MASCC score, with 3% if score >21, and up to 36% if score <15 3, 4

The duration of neutropenia is a critical risk factor for infection severity, with protracted neutropenia (≥7 days) associated with higher risk 8
Symptoms and signs of inflammation may be minimal or absent in severely neutropenic patients, making fever often the only sign of infection 7
At least half of neutropenic patients who become febrile have an established or occult infection, and at least one-fifth of patients with neutrophil counts <100 cells/mm³ have bacteremia 7
Prompt initiation of empirical broad-spectrum antibiotics is crucial, as infection can progress rapidly in neutropenic patients, and the choice of empirical therapy should be guided by local antimicrobial resistance patterns and individual patient risk factors 2, 3, 4, 5