Pneumonia Severity Scoring and Treatment Approach
Recommended Scoring System
Use CRB65 (or CURB-65 when laboratory testing is available) as the primary severity assessment tool for pneumonia, as it provides a simple, validated approach to risk stratification and guides site-of-care decisions. 1
CRB65 Scoring Components
The score includes one point for each of the following criteria: 1
- Confusion (new disorientation in person, place, or time)
- Raised respiratory rate (≥30 breaths/min)
- Low Blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg)
- Age ≥65 years
Risk Stratification and Mortality
The 30-day mortality risk increases directly with score: 1, 2
- Score 0: <1% mortality risk (low risk)
- Score 1-2: 1-10% mortality risk (intermediate risk)
- Score 3-4: >10% mortality risk (high risk)
More specifically, validated data shows mortality of 0.7%, 2.1%, 9.2%, 14.5%, 40%, and 60% for scores of 0,1,2,3,4, and 5 respectively when using the full CURB-65. 1, 2
Treatment Approach Based on Score
Outpatient Management (CRB65 Score 0)
Consider home-based care for patients with CRB65 score of 0. 1
- These patients have <1% mortality risk and can be safely managed as outpatients 1
- Ensure ability to safely take oral medications and availability of outpatient support resources 1
Hospital Assessment Required (CRB65 Score ≥2)
Consider hospital assessment for patients with CRB65 score of 2 or more. 1
- Discuss shared decision-making about care pathways, including supported home-based care using virtual wards or community intervention teams 1
- More intensive treatment (hospitalization or intensive in-home health services) is warranted for CURB-65 scores ≥2 1
Adjunctive Testing with C-Reactive Protein
When uncertainty exists about antibiotic necessity, point-of-care CRP testing can inform decisions: 1
- CRP >100 mg/L: Consider immediate antibiotics
- CRP 20-100 mg/L: Consider back-up antibiotic prescription
- CRP <20 mg/L: Do not routinely offer antibiotics
ICU Admission Criteria
Direct ICU admission is required for patients with: 1
- Septic shock requiring vasopressors (major criterion)
- Acute respiratory failure requiring intubation and mechanical ventilation (major criterion)
Consider ICU admission for patients with ≥3 of the following minor criteria: 1
- Respiratory rate ≥30 breaths/min
- PaO₂/FiO₂ ratio <250
- Multilobar infiltrates
- Confusion
- Blood urea nitrogen ≥20 mg/dL
- Leukopenia from infection
- Thrombocytopenia
- Hypothermia
- Hypotension requiring aggressive fluid resuscitation
Alternative Scoring: Pneumonia Severity Index (PSI)
While the Infectious Diseases Society of America and American Thoracic Society endorse both CURB-65 and PSI, PSI is more complex, requiring calculation of 20 variables, making it challenging in emergency settings. 1, 3
PSI stratifies patients into five risk classes: 4
- Classes I-III: ≤3% mortality (outpatient candidates)
- Class IV: 8% mortality (hospitalization)
- Class V: 35% mortality (hospitalization)
A 2023 meta-analysis found CURB-65 slightly superior to PSI for early mortality prediction and ICU admission decisions, with 96.7% sensitivity and 89.3% specificity for predicting need for intensive care support. 5
Critical Caveats
Age-Related Limitations
- In patients <65 years, consider using CRB-50 (age ≥50) instead, as it performs better in younger populations (0.730 AUC vs 0.690 for CRB-80). 6
- In nursing home-acquired pneumonia, even CRB-80 fails to identify low-risk patients (22.75% mortality in "low-risk" group), requiring additional assessment of functional status and comorbidities. 6
Clinical Judgment Override
Objective scores must always be supplemented with physician assessment of subjective factors. 1
- Ability to safely and reliably take oral medications
- Availability of outpatient support resources
- Comorbidities and pregnancy status may affect score interpretation 1
Diagnostic Requirements
A demonstrable infiltrate by chest radiograph or other imaging is required for pneumonia diagnosis, regardless of clinical features. 1