CURB-65 Management Approach for Community-Acquired Pneumonia
Use CURB-65 to stratify pneumonia patients into risk categories that directly determine site-of-care: scores 0-1 warrant outpatient treatment, score 2 requires hospitalization or intensive home monitoring, and scores ≥3 mandate hospital admission with prompt ICU assessment. 1, 2
Understanding the CURB-65 Score
The score assigns one point for each of the following five criteria present at initial assessment: 3, 1
- Confusion (mental test score <8, or new disorientation to person, place, or time)
- Urea >7 mmol/L (or BUN >19 mg/dL)
- Respiratory rate ≥30 breaths/min
- Blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg)
- 65 years of age or older
Risk Stratification and Mortality Prediction
The mortality risk increases directly with score: 1, 2, 4
- Score 0: 0.7% mortality
- Score 1: 2.1% mortality
- Score 2: 9.2% mortality
- Score 3: 14.5% mortality
- Score 4: 40% mortality
- Score 5: 57% mortality
Management Algorithm by CURB-65 Score
CURB-65 Score 0-1: Outpatient Treatment
These patients can be safely managed as outpatients with oral antibiotics. 3, 1
- For previously healthy adults without comorbidities: amoxicillin 1g three times daily or doxycycline 100mg twice daily 2
- For adults with comorbidities (COPD, diabetes, heart disease, prior antibiotic use): combination therapy with amoxicillin/clavulanate or cephalosporin plus macrolide 2
- Clinical improvement should occur within 3 days; patients must contact their physician if no improvement 2
CURB-65 Score 2: Hospitalization or Intensive Outpatient Monitoring
This intermediate-risk group faces 9.2% mortality and requires more intensive management—either short-stay hospitalization or hospital-supervised outpatient treatment. 3, 1 This decision requires clinical judgment considering: 3
- Comorbidities not captured by CURB-65 (HIV, active malignancy, severe COPD)
- Social factors (homelessness, inability to reliably take medications, lack of social support)
- Failure of prior outpatient antibiotic therapy
- Ability to maintain oral intake
CURB-65 Score ≥3: Hospital Admission with ICU Assessment
Patients with scores of 3,4, or 5 are at high risk of death (14.5-57% mortality) and must be hospitalized with prompt evaluation for ICU care. 3, 1
Mandatory investigations for hospitalized patients include: 3
- Full blood count, urea and electrolytes, liver function tests
- Chest radiography
- Pulse oximetry (if <92% on room air, obtain arterial blood gases)
- Blood cultures (before antibiotics)
- Pneumococcal and Legionella urine antigens
- Sputum gram stain and culture (if able to expectorate and no prior antibiotics)
Critical ICU Transfer Criteria
CURB-65 alone performs poorly for ICU triage decisions (sensitivity only 78.4% for predicting critical care interventions). 1, 5 Instead, use IDSA/ATS severe CAP criteria for ICU admission: 1, 2
Direct ICU admission is required for: 1, 6
- Septic shock requiring vasopressors
- Acute respiratory failure requiring intubation and mechanical ventilation
Consider ICU/HDU transfer for patients with CURB-65 scores 4-5 or any of the following: 3, 1, 6
- Persisting hypoxia with PaO₂ <8 kPa despite maximal oxygen
- Progressive hypercapnia
- Severe acidosis (pH <7.26)
- Meeting ≥3 minor IDSA/ATS criteria (respiratory rate ≥30/min, PaO₂/FiO₂ ratio ≤250, multilobar infiltrates, confusion, uremia, leukopenia, thrombocytopenia, hypothermia, hypotension requiring aggressive fluid resuscitation)
Clinical Override Situations
Certain clinical scenarios mandate hospital admission regardless of CURB-65 score: 3, 6
- Bilateral lung infiltrates on chest radiography consistent with primary viral pneumonia
- Oxygen saturation <90-92% on room air
- Signs of respiratory failure (persistent hypoxia, progressive hypercapnia)
- Septic shock with organ dysfunction
Important Pitfalls and Limitations
Age-Related Underestimation
CURB-65 may underestimate severity in young patients (<65 years) with severe respiratory failure who lack age points despite significant physiologic derangement. 1, 2 Look for severe tachypnea, hypoxemia, or multilobar infiltrates in younger patients that warrant admission despite low scores.
ICU Prediction Limitations
Research shows that 15.6% of patients with CURB-65 scores 0-1 were admitted to ICU, and 6.4% received critical care interventions. 5 Among patients with score 2,27% required ICU admission and 15.4% received critical care interventions. 5 This demonstrates that CURB-65 should guide but not replace clinical judgment for disposition decisions.
Elderly Patients with Comorbidities
Elderly patients with multiple comorbidities may have falsely elevated CURB-65 scores without true severity. 1 Consider baseline functional status and whether acute decompensation is truly present.
Simplified Alternative: CRB-65
When laboratory testing is unavailable (primary care settings, resource-limited environments), use CRB-65, which omits the urea measurement and gives a point range from 0 to 4. 3, 1 This variant is particularly useful in outpatient settings for initial triage decisions. 1, 6
Comparative Performance
CURB-65 is simpler than the Pneumonia Severity Index (PSI), requiring only 5 variables versus 20, making it more practical in busy emergency departments. 3, 7 While PSI may identify slightly more low-risk patients, CURB-65 has higher specificity (74.6% vs 52.2%) for predicting mortality and is easier to remember and calculate at the point of care. 3, 8 Recent meta-analysis shows CURB-65 has slightly better sensitivity (96.7%) and specificity (89.3%) for predicting ICU admission compared to PSI. 9