Febrile Neutropenia — Part 1: Definition, Risk Stratification & Initial Evaluation
Definitions of febrile neutropenia, MASCC risk index, CISNE score, high-risk versus low-risk classification, and comprehensive initial workup including history, physical examination, laboratory studies, blood cultures, and imaging.
1. Definition of Febrile Neutropenia
1.1 Standard Definition
Febrile neutropenia (FN) is defined by the concurrent presence of fever and neutropenia in a patient receiving myelosuppressive therapy.1 2
Fever is defined as:
- A single oral temperature of ≥ 38.3 °C (101.0 °F), OR
- A sustained oral temperature of ≥ 38.0 °C (100.4 °F) for ≥ 1 hour
Neutropenia is defined as:
- An absolute neutrophil count (ANC) of < 500 cells/μL, OR
- An ANC of < 1,000 cells/μL with a predicted decline to < 500 cells/μL over the next 48 hours
1.2 Important Clinical Considerations
- Temperature measurement: Oral temperature is the recommended method. Axillary temperatures may underestimate true core temperature by 0.5–1.0 °C. Rectal temperatures should be avoided in neutropenic patients because of the risk of perianal mucosal disruption and translocation of enteric organisms.1
- Blunted febrile response: Some patients, particularly those receiving corticosteroids, may not mount a febrile response despite active infection. A high index of clinical suspicion should be maintained in any neutropenic patient with signs or symptoms of infection regardless of temperature.
- ANC calculation: ANC = total white blood cell count (cells/μL) × (% segmented neutrophils + % band forms) / 100.
- Profound neutropenia: An ANC of < 100 cells/μL is considered profound neutropenia and carries the highest risk for infectious complications.2
- Duration of neutropenia: Expected duration of neutropenia > 7 days is a key determinant of infection risk and influences management decisions.1
1.3 Severity Classification by ANC
| ANC (cells/μL) | Severity Classification | Clinical Significance |
|---|---|---|
| 500–1,000 | Mild neutropenia | Modestly increased infection risk |
| 100–499 | Severe neutropenia | Substantially increased infection risk; meets FN criteria |
| < 100 | Profound neutropenia | Highest risk for serious bacterial and fungal infections |
2. Risk Stratification
Risk stratification is essential in febrile neutropenia to identify patients who may be safely managed as outpatients with oral antibiotics versus those who require inpatient intravenous therapy and close monitoring. Two validated scoring systems are widely recommended.1 2 3
2.1 MASCC Risk Index
The Multinational Association for Supportive Care in Cancer (MASCC) risk index is the most widely validated tool for identifying low-risk FN patients. It was developed from a multinational prospective study of 756 patients and validated in 539 patients.4
Complete MASCC Scoring Table
| Characteristic | Weight (Points) |
|---|---|
| Burden of febrile neutropenia (choose only one): | |
| — No or mild symptoms | 5 |
| — Moderate symptoms | 3 |
| — Severe symptoms or moribund | 0 |
| No hypotension (systolic BP > 90 mmHg) | 5 |
| No chronic obstructive pulmonary disease | 4 |
| Solid tumor or hematologic malignancy with no previous fungal infection | 4 |
| No dehydration requiring parenteral fluids | 3 |
| Outpatient status at onset of fever | 3 |
| Age < 60 years | 2 |
Maximum possible score: 26
Risk Classification
| MASCC Score | Risk Category | Predicted Serious Complication Rate | Predicted Mortality |
|---|---|---|---|
| ≥ 21 | Low risk | ~6% | ~1% |
| < 21 | High risk | ~39% | ~14% |
MASCC Scoring Notes
- The “burden of febrile neutropenia” is a subjective clinical assessment by the treating physician at the time of presentation. The three categories (no/mild, moderate, severe/moribund) are mutually exclusive — only one may be selected, and the weights are not additive.4
- The MASCC score should be calculated at the initial presentation of the febrile neutropenia episode.
- In the original validation study, a score ≥ 21 had a positive predictive value of 91% for identifying low-risk patients, with a specificity of 68% and sensitivity of 71%.4
- The MASCC score does not incorporate the expected duration of neutropenia, which is a significant limitation. Patients with anticipated prolonged neutropenia (> 7 days) may be misclassified as low risk.
2.2 Clinical Index of Stable Febrile Neutropenia (CISNE)
The CISNE score was developed specifically for patients with apparently stable episodes of FN (i.e., patients who appear clinically well at presentation). It was designed to improve upon the MASCC index by identifying occult complications in seemingly low-risk patients.5
Complete CISNE Scoring Table
| Variable | Points |
|---|---|
| Eastern Cooperative Oncology Group (ECOG) performance status ≥ 2 | 2 |
| Chronic obstructive pulmonary disease | 1 |
| Chronic cardiovascular disease | 1 |
| Mucositis grade ≥ 2 (NCI-CTCAE) | 1 |
| Monocyte count < 200 cells/μL | 1 |
| Stress-induced hyperglycemia (glucose ≥ 250 mg/dL in non-diabetic patients, or ≥ 121 mg/dL requiring new insulin initiation) | 2 |
Score range: 0–8
CISNE Risk Categories
| CISNE Score | Risk Category | Complication Rate | Recommended Management |
|---|---|---|---|
| 0 | Low risk (I) | ~1.1% | May be candidates for outpatient management |
| 1–2 | Intermediate risk (II) | ~6.2% | Inpatient management generally recommended |
| ≥ 3 | High risk (III) | ~36% | Inpatient management required |
CISNE Application Notes
- CISNE is intended only for patients who appear clinically stable at presentation — it should not be applied to hemodynamically unstable, critically ill, or overtly septic patients.5
- CISNE was validated primarily in solid tumor patients and may have limited applicability in hematologic malignancies with expected prolonged neutropenia.
- The CISNE score is complementary to, not a replacement for, the MASCC index. Some guidelines recommend using both scores in conjunction.
2.3 Comprehensive High-Risk vs. Low-Risk Criteria
Beyond the MASCC and CISNE scores, several additional clinical factors inform risk classification.1 2 3
High-Risk Features (Any of the Following)
| Category | High-Risk Criterion |
|---|---|
| Duration of neutropenia | ANC < 500 cells/μL expected to last > 7 days |
| Depth of neutropenia | ANC < 100 cells/μL (profound neutropenia) |
| Hemodynamic instability | Hypotension (systolic BP < 90 mmHg), sepsis, or septic shock |
| Malignancy type | Acute leukemia undergoing induction chemotherapy; allogeneic or autologous hematopoietic stem cell transplant (HSCT) recipients in the pre-engraftment period |
| Organ dysfunction | New hepatic insufficiency (transaminases > 5× ULN), renal insufficiency (creatinine clearance < 30 mL/min), or altered mental status |
| Gastrointestinal symptoms | Clinically significant mucositis (grade 3–4), abdominal pain, nausea/vomiting/diarrhea precluding oral medication absorption |
| Pulmonary infiltrates | New pulmonary infiltrates on imaging, hypoxemia, or underlying chronic lung disease |
| Documented infection | Pneumonia, central line infection, soft tissue infection, or other documented source at presentation |
| Comorbidities | Uncontrolled or progressive cancer, significant medical comorbidities (COPD, heart failure, diabetes mellitus with poor control) |
| Outpatient compliance | Inability to comply with outpatient follow-up requirements, including lack of caregiver, distance from medical facility > 1 hour, or patient preference for inpatient care |
| Scoring systems | MASCC score < 21 or CISNE score ≥ 3 |
Low-Risk Features (All Must Be Present)
| Category | Low-Risk Criterion |
|---|---|
| Duration of neutropenia | ANC expected to recover within ≤ 7 days |
| Clinical stability | Hemodynamically stable, no signs of sepsis |
| Malignancy type | Solid tumor, or hematologic malignancy without intensive induction |
| Organ function | No significant hepatic or renal dysfunction |
| GI function | Intact GI tract, able to tolerate oral medications |
| No documented source | No pneumonia, line infection, or complicated soft tissue infection |
| Social factors | Adequate home support, able to return to emergency care within 1 hour, reliable communication access |
| Scoring systems | MASCC score ≥ 21 AND CISNE score 0 (if applicable) |
3. Initial Evaluation and Workup
The evaluation of a patient with suspected febrile neutropenia must be rapid and systematic. Empiric antibiotics should be administered within 60 minutes of presentation — ideally within 30 minutes — as delays in antibiotic administration are associated with increased mortality.1 2 6
3.1 Triage Principles
- Febrile neutropenia should be treated as a medical emergency.
- Patients presenting to the emergency department or calling their oncologist with fever during an expected period of neutropenia should be triaged for immediate evaluation.
- Blood cultures and laboratory studies should be obtained before antibiotics but should never delay antibiotic initiation by more than a few minutes. If venous access is difficult, antibiotics should be started and cultures obtained as soon as possible thereafter.
3.2 History
A focused history should address:
| Domain | Specific Elements |
|---|---|
| Chemotherapy details | Regimen, cycle number, date of most recent chemotherapy, and nadir timing |
| Fever history | Time of onset, maximum temperature, associated rigors or chills |
| Localizing symptoms | Cough, dyspnea, sore throat, odynophagia, chest pain, abdominal pain, diarrhea, dysuria, frequency, skin changes, perianal pain, headache, mental status changes |
| Oral status | Mucositis severity, ability to swallow medications |
| Central venous access | Type of device (port, PICC, tunneled catheter), date of insertion, recent use, signs of tunnel or exit site infection |
| Prior infections | History of prior FN episodes, documented organisms, resistant pathogens, fungal infections |
| Antimicrobial exposure | Current prophylactic antibiotics, recent therapeutic antibiotics, recent antifungal or antiviral therapy |
| Exposures | Sick contacts, travel history, animal exposures, food exposures |
| Comorbidities | COPD, diabetes mellitus, liver disease, renal disease, HIV, prior splenectomy |
| Functional status | ECOG performance status, ability to perform activities of daily living |
| Social factors | Home support, distance from hospital, ability to return promptly if condition worsens |
3.3 Physical Examination
A thorough physical examination is essential, with particular attention to areas that are common sites of infection in neutropenic patients. The absence of neutrophils may attenuate typical signs of inflammation (e.g., fluctuance, erythema, purulence), so subtle findings must be sought.1
| Site | Examination Focus |
|---|---|
| Vital signs | Temperature (oral), heart rate, blood pressure, respiratory rate, oxygen saturation |
| Oropharynx | Mucositis, ulcers, thrush, gingival erythema or swelling, dental abscess |
| Skin | Cellulitis, ecthyma gangrenosum (suggestive of Pseudomonas), vesicular lesions (HSV, VZV), catheter site erythema, tenderness, or drainage |
| Central line sites | Tunnel tract tenderness, exit site erythema/discharge, port pocket erythema |
| Lungs | Auscultation for crackles, decreased breath sounds, or signs of consolidation (may be absent in profound neutropenia) |
| Abdomen | Tenderness (particularly right lower quadrant — neutropenic enterocolitis/typhlitis), distention, peritoneal signs |
| Perianal region | Erythema, tenderness, fissures, fluctuance — visual inspection only; digital rectal examination is contraindicated in neutropenic patients |
| Neurologic | Mental status, nuchal rigidity, focal deficits |
3.4 Laboratory Studies
| Test | Rationale |
|---|---|
| Complete blood count with differential | Confirm ANC, assess for anemia and thrombocytopenia |
| Comprehensive metabolic panel | Assess hepatic and renal function, electrolytes, glucose |
| Lactate | Screen for occult tissue hypoperfusion; elevated lactate (> 2 mmol/L) suggests higher acuity |
| C-reactive protein (CRP) | May aid in risk assessment; rising CRP associated with bacteremia |
| Procalcitonin | Consider in patients with suspected bacterial infection; may have role in guiding antibiotic de-escalation (evidence is evolving) |
| Urinalysis | May lack pyuria in neutropenic patients despite urinary tract infection; low sensitivity in profound neutropenia |
| Coagulation studies | PT/INR, aPTT if disseminated intravascular coagulation is suspected or if procedures are anticipated |
3.5 Microbiologic Cultures
Blood cultures are the single most important microbiologic study in febrile neutropenia.1 2
Blood Culture Protocol
| Parameter | Recommendation |
|---|---|
| Number of sets | Minimum 2 sets (1 set = 1 aerobic bottle + 1 anaerobic bottle) |
| Central line cultures | If central venous catheter (CVC) is present: obtain at least 1 set from each lumen of the CVC and at least 1 set from a peripheral vein |
| Peripheral-only | If no CVC: obtain 2 sets from 2 separate peripheral venipuncture sites |
| Volume per bottle | 8–10 mL of blood per bottle (20 mL per set); inadequate volume is the most common cause of false-negative blood cultures |
| Differential time to positivity | If CVC cultures become positive ≥ 2 hours before peripheral cultures, this suggests a catheter-related bloodstream infection (CRBSI) |
| Timing | Obtain before antibiotics whenever possible; do not delay antibiotics > 30 minutes to obtain cultures |
Additional Cultures (as Clinically Indicated)
| Specimen | Indication |
|---|---|
| Urine culture | Urinary symptoms, indwelling urinary catheter, or urinalysis abnormalities |
| Sputum culture | Productive cough; yield is low in neutropenic patients and should not delay therapy |
| Wound/skin culture | Skin lesions, cellulitis, catheter exit site drainage |
| Stool studies | Diarrhea: Clostridioides difficile testing (PCR or GDH/toxin); consider stool culture or gastrointestinal pathogen panel |
| Respiratory viral panel | Upper or lower respiratory symptoms, especially during respiratory virus season |
| Cerebrospinal fluid | Signs of meningitis or encephalitis (ensure platelet count is adequate before lumbar puncture) |
| Fungal cultures | Suspected invasive fungal infection (blood fungal cultures, tissue biopsy) |
| Galactomannan / beta-D-glucan | Suspected invasive aspergillosis (serum galactomannan) or invasive fungal infection (serum 1,3-beta-D-glucan) |
3.6 Imaging
Imaging is guided by clinical findings and should not delay initiation of empiric therapy.1 2
| Study | Indication |
|---|---|
| Chest radiograph | All patients with respiratory symptoms (cough, dyspnea, hypoxia); consider in all high-risk patients even without respiratory symptoms |
| CT chest | Persistent or recurrent fever despite 4–7 days of broad-spectrum antibiotics; new respiratory symptoms; known or suspected invasive pulmonary aspergillosis (CT is more sensitive than chest radiograph for detecting early fungal pneumonia — may show halo sign or air-crescent sign) |
| CT abdomen/pelvis | Abdominal pain, diarrhea, suspected typhlitis (neutropenic enterocolitis), perianal symptoms |
| CT sinuses | Facial pain, nasal congestion, or epistaxis in patients with prolonged neutropenia (concern for invasive fungal sinusitis) |
| CT or MRI brain | Altered mental status, focal neurologic deficits, headache with meningeal signs |
3.7 Initial Risk Assessment Algorithm
The following stepwise approach integrates the evaluation components into a practical clinical workflow:
- Confirm febrile neutropenia — Verify temperature ≥ 38.3 °C (single) or ≥ 38.0 °C (sustained ≥ 1 hour) AND ANC < 500 cells/μL or < 1,000 cells/μL with expected decline.
- Obtain cultures and labs — Blood cultures (2 sets, including from all CVC lumens), CBC with differential, CMP, lactate; additional cultures based on symptoms.
- Start empiric antibiotics within 60 minutes — Do not wait for culture results or imaging.
- Complete physical examination — Systematic assessment with attention to common infection sites.
- Perform imaging as indicated — Chest radiograph if respiratory symptoms; CT as clinically warranted.
- Calculate MASCC score — Determine risk category.
- Apply CISNE score — For apparently stable patients, calculate CISNE to further refine risk.
- Assess additional high-risk features — Review expected duration of neutropenia, malignancy type, organ function, social factors.
- Classify as high risk or low risk — This determination guides subsequent management (inpatient IV therapy vs. potential outpatient oral therapy).
References
Freifeld AG, Bow EJ, Sepkowitz KA, et al. Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the Infectious Diseases Society of America (IDSA). Clin Infect Dis. 2011;52(4):e56-e93. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Taplitz RA, Kennedy EB, Bow EJ, et al. Outpatient management of fever and neutropenia in adults treated for malignancy: American Society of Clinical Oncology (ASCO) and Infectious Diseases Society of America (IDSA) clinical practice guideline update. J Clin Oncol. 2018;36(14):1443-1453. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Klastersky J, de Naurois J, Rolston K, et al. Management of febrile neutropaenia: ESMO clinical practice guidelines. Ann Oncol. 2016;27(suppl 5):v111-v118. ↩︎ ↩︎
Klastersky J, Paesmans M, Rubenstein EB, et al. The Multinational Association for Supportive Care in Cancer (MASCC) risk index: a multinational scoring system for identifying low-risk febrile neutropenic cancer patients. J Clin Oncol. 2000;18(16):3038-3051. ↩︎ ↩︎ ↩︎
Carmona-Bayonas A, Jimenez-Fonseca P, Virizuela Echaburu J, et al. Prediction of serious complications in patients with seemingly stable febrile neutropenia: validation of the Clinical Index of Stable Febrile Neutropenia (CISNE) in a prospective cohort of patients from the FINITE study. J Clin Oncol. 2015;33(5):465-471. ↩︎ ↩︎
Rosa RG, Goldani LZ. Cohort study of the impact of time to antibiotic administration on mortality in patients with febrile neutropenia. Antimicrob Agents Chemother. 2014;58(7):3799-3803. ↩︎