What is the recommended mortality risk score for assessing pneumonia?

Recommended Mortality Risk Scores for Pneumonia Assessment

The Pneumonia Severity Index (PSI) is the preferred mortality risk score for assessing pneumonia severity and determining the need for hospitalization in adults with community-acquired pneumonia. 1

Primary Risk Assessment Tools

Pneumonia Severity Index (PSI)

• PSI is strongly recommended by the 2019 American Thoracic Society/Infectious Diseases Society of America guidelines as the preferred tool for determining hospitalization needs 1
• Incorporates 20 variables including demographics, comorbidities, vital signs, laboratory values, and radiographic findings 1
• Effectively stratifies patients into five risk classes with corresponding mortality risks:
  • Classes I-III: ≤3% mortality (candidates for outpatient treatment)
  • Class IV: 8% mortality (consider hospitalization)
  • Class V: 35% mortality (hospitalization recommended) 1, 2
• Primarily designed to identify low-risk patients who can safely be treated as outpatients 2
• Has been extensively validated in multiple studies 2

CURB-65 Score

• Alternative to PSI, particularly useful when laboratory testing is limited 1
• Simpler calculation with only 5 variables: Confusion, Urea (BUN), Respiratory rate, Blood pressure, and age ≥65 years 1, 3
• Risk stratification:
  • 0-1 points: 0.7-2.1% mortality (outpatient treatment)
  • 2 points: 9.2% mortality (short hospital stay or supervised outpatient)
  • 3 points: 14.5% mortality (hospital admission, assess for ICU)
  • 4-5 points: 40-57% mortality (hospital admission, assess for ICU) 1, 3
• More practical in emergency settings due to simplicity 3

CRB-65 Score

• Simplified version of CURB-65 that omits blood urea nitrogen testing 1
• Particularly useful in outpatient settings where laboratory tests aren't readily available 3, 4
• Demonstrated good predictive value for mortality in both inpatient and outpatient settings 4

Choosing Between PSI and CURB-65

Advantages of PSI

• More extensively validated than CURB-65 1
• More accurate for identifying low-risk patients who can be safely treated as outpatients 1, 2
• Provides more granular risk stratification with its five classes 2
• Strongly recommended by the 2019 ATS/IDSA guidelines 1

Advantages of CURB-65

• Simpler to calculate with only 5 variables (vs. 20 for PSI) 1, 3
• Easier to remember and apply at the point of care 5, 3
• Requires only one laboratory test (BUN) 3
• Recent meta-analysis suggests CURB-65 may be slightly better in early mortality prediction and has higher sensitivity (96.7%) and specificity (89.3%) for predicting ICU admission 6

ICU Admission Criteria

• For ICU admission decisions, the 2007 IDSA/ATS severe CAP criteria are more accurate than either PSI or CURB-65 1, 5
• Direct ICU admission is required for patients with:
  • Major criteria: Septic shock requiring vasopressors or acute respiratory failure requiring intubation and mechanical ventilation 1
  • Minor criteria: Three or more of the minor criteria for severe CAP 1
• CURB-65 alone has relatively low sensitivity (78.4%) for predicting critical care interventions 7

Implementation Considerations

• Both PSI and CURB-65 should be used as adjuncts to clinical judgment, not as the sole determinants for hospitalization decisions 1, 3
• PSI may underestimate severity in young patients with severe respiratory failure due to its heavy weighting of age 1, 2
• CURB-65 may underestimate risk in elderly patients with comorbidities 1
• Studies show that only 5.2% of CAP patients had CURB-65 scores applied at admission in routine practice, suggesting implementation challenges 8
• Recent evidence suggests CURB-65 may also have value in predicting longer-term mortality (up to 6 months) 9

Algorithm for Risk Score Selection

1. For initial site-of-care decisions: Use PSI when comprehensive laboratory data is available; use CURB-65 when rapid assessment is needed or laboratory access is limited 1, 3
2. For ICU admission decisions: Apply the 2007 IDSA/ATS severe CAP criteria rather than relying solely on PSI or CURB-65 1, 5
3. For outpatient settings: Consider CRB-65 when laboratory testing is unavailable 3, 4