PSI/PORT Score Calculator
Pneumonia Severity Index / Patient Outcomes Research Team
The PSI/PORT Score is a clinical prediction rule that assesses mortality risk in patients with community-acquired pneumonia (CAP). It helps clinicians determine the appropriate site of care—outpatient, inpatient, or intensive care—based on the patient’s risk of death.
Patient Assessment
Automatic Risk Class V Criteria
If any of these criteria are present, the patient is automatically assigned to Risk Class V (highest risk):
Demographic Factors
+Physical Examination
+Laboratory & Radiographic Findings
+PSI Scoring System
The PSI score is calculated by assigning points to demographic factors, comorbidities, physical exam findings, and laboratory results. Patients with any automatic Class V criteria are immediately assigned to the highest risk category.
PSI/PORT Score Results
Interpretation
The PSI score of 51 places this patient in Risk Class II, indicating a low mortality risk of 0.6%. Patients in this risk class can generally be safely managed as outpatients with appropriate oral antibiotic therapy.
Risk Classification
| Risk Class | PSI Score | 30-Day Mortality | Risk Level |
|---|---|---|---|
| I | ≤ 50 | 0.1% | Lowest |
| II | 51-70 | 0.6% | Low |
| III | 71-90 | 0.9% | Low |
| IV | 91-130 | 9.3% | Moderate |
| V | > 130 | 27.0% | High |
Recommended Site of Care
Low-risk patients (Classes I-III) can be safely treated at home with oral antibiotics and close follow-up.
Moderate-risk patients (Class IV) require hospital admission for IV antibiotics and monitoring.
High-risk patients (Class V) often require intensive care with possible respiratory support.
Clinical Recommendations
- Treat with appropriate oral antibiotics for community-acquired pneumonia
- Schedule follow-up within 48-72 hours to assess response
- Provide clear instructions for when to seek urgent care
- Consider social factors and ability to adhere to treatment
PSI vs. CURB-65
The PSI score is more comprehensive than CURB-65 but requires more data. CURB-65 is simpler and useful for rapid emergency department assessment.
PSI Advantage: More accurate risk stratification, especially for low-risk patients.
CURB-65 Advantage: Quicker assessment with only 5 variables.
The PSI/PORT Score (Pneumonia Severity Index/Patient Outcomes Research Team) is a clinical prediction rule that assesses mortality risk in patients with community-acquired pneumonia (CAP). It helps clinicians determine the appropriate site of care—outpatient, inpatient, or intensive care—based on the patient’s risk of death.
Purpose and Clinical Utility
Primary Objectives
- Risk Stratification: Identify patients at low risk who can be safely treated as outpatients
- Site-of-Care Decisions: Guide appropriate hospitalization vs. outpatient management
- Mortality Prediction: Estimate 30-day mortality risk
- Resource Allocation: Optimize healthcare resource utilization
- Quality Benchmarking: Compare outcomes across healthcare institutions
Key Advantages
- Evidence-Based: Derived from large multicenter studies
- Validated: Extensively validated across diverse populations
- Comprehensive: Incorporates multiple clinical and demographic factors
- Clinical Impact: Reduces unnecessary hospitalizations for low-risk patients
Calculation Methodology
The PSI score is calculated through a two-step process:
Step 1: Identify High-Risk Patients (Class V)
Patients are immediately assigned to Risk Class V (highest risk) if they have any of the following:
- Age > 80 years
- Nursing home residence
- Coexisting neoplastic disease
- Congestive heart failure
- Cerebrovascular disease
- Renal disease
- Liver disease
Step 2: Score Calculation for Other Patients
For patients not in Class V, points are assigned across 20 variables:
Demographic Factors
- Age: Points equal to age in years for men; age minus 10 for women
- Nursing home resident: +10 points
Comorbid Conditions
- Neoplastic disease: +30 points
- Liver disease: +20 points
- Congestive heart failure: +10 points
- Cerebrovascular disease: +10 points
- Renal disease: +10 points
Physical Examination Findings
- Altered mental status: +20 points
- Respiratory rate ≥ 30/min: +20 points
- Systolic BP < 90 mmHg: +20 points
- Temperature < 35°C or ≥ 40°C: +15 points
- Pulse ≥ 125/min: +10 points
Laboratory and Radiographic Findings
- Arterial pH < 7.35: +30 points
- BUN ≥ 30 mg/dL: +20 points
- Sodium < 130 mEq/L: +20 points
- Glucose ≥ 250 mg/dL: +10 points
- Hematocrit < 30%: +10 points
- PaO₂ < 60 mmHg or O₂ saturation < 90%: +10 points
- Pleural effusion: +10 points
Risk Classification and Interpretation
| Risk Class | PSI Score | Mortality Risk | Recommended Site of Care |
|---|---|---|---|
| I | ≤ 50 points | 0.1% | Outpatient treatment |
| II | 51-70 points | 0.6% | Outpatient treatment |
| III | 71-90 points | 0.9% | Brief hospitalization or observation |
| IV | 91-130 points | 9.3% | Inpatient treatment |
| V | > 130 points | 27.0% | Inpatient treatment, consider ICU |
Clinical Applications
Low-Risk Patients (Classes I-III)
- Outpatient Management: Safe for home treatment with oral antibiotics
- Cost-Effective: Reduces healthcare costs without compromising outcomes
- Patient Satisfaction: Prevents unnecessary hospitalizations
Moderate-Risk Patients (Class IV)
- Inpatient Management: Requires hospital admission
- Intravenous Antibiotics: Initial IV therapy with transition to oral
- Close Monitoring: Regular assessment for clinical deterioration
High-Risk Patients (Class V)
- Aggressive Management: Often requires ICU-level care
- Broad-Spectrum Coverage: Empiric antibiotics covering resistant organisms
- Multidisciplinary Approach: May require respiratory support, vasopressors
Comparison with Other Pneumonia Scores
CURB-65
- Simpler: Only 5 variables (Confusion, Urea, Respiratory rate, Blood pressure, Age ≥65)
- Less Comprehensive: May miss some high-risk patients
- Quick Assessment: Useful in emergency department settings
SMART-COP
- ICU Prediction: Specifically designed to identify need for ICU admission
- Vasopressor Focus: Includes blood pressure and pH criteria
- Younger Patients: May perform better in younger populations
Validation and Performance
Original PORT Study
- Sample Size: 14,199 adult inpatients with CAP
- Development: 2,287 patients from 1989
- Validation: 2,287 patients from 1991
- Geographic Diversity: 5 study sites across US and Canada
Performance Characteristics
- Discrimination: Excellent (c-statistic 0.81-0.88)
- Calibration: Good across different populations
- Generalizability: Validated in international settings
Limitations and Considerations
Clinical Limitations
- Complex Calculation: 20 variables make manual calculation challenging
- Age Dominance: Heavy weighting on age may underestimate risk in younger patients
- Comorbidity Focus: May miss acute physiological derangements
- Nursing Home Bias: Automatic Class V assignment may overestimate risk
Practical Considerations
- Clinical Judgment: Should complement, not replace, clinical assessment
- Social Factors: Does not account for homelessness, substance abuse, or inadequate home support
- Pathogen-Specific: Does not consider specific microorganisms
- Dynamic Changes: Single assessment may not capture clinical trajectory
Special Populations
Elderly Patients
- Higher baseline risk due to age and comorbidities
- May require hospitalization for social reasons despite low PSI
- Increased risk of functional decline post-pneumonia
Immunocompromised Patients
- PSI may underestimate risk in HIV, transplant, or chemotherapy patients
- Requires additional considerations for opportunistic pathogens
- Lower threshold for hospitalization
Young Adults
- PSI may underestimate severity in young patients with no comorbidities
- Consider additional factors like substance use, social determinants
Implementation in Clinical Practice
Electronic Health Records
- Automated Calculation: Built-in calculators in EHR systems
- Clinical Decision Support: Alerts for high-risk patients
- Quality Metrics: Tracking adherence to site-of-care recommendations
Emergency Department Use
- Rapid Triage: Quick identification of low-risk patients for discharge
- Resource Allocation: Appropriate bed assignment (ward vs. ICU)
- Antibiotic Stewardship: Guides empiric antibiotic selection
Inpatient Management
- Severity Assessment: Helps determine monitoring intensity
- Discharge Planning: Identifies patients ready for transition to oral therapy
- Prognostic Counseling: Provides mortality risk information for patients/families
Recent Updates and Modifications
PSI with Procalcitonin
- Biomarker Addition: Incorporates procalcitonin levels for antibiotic guidance
- Enhanced Specificity: May improve identification of bacterial vs. viral pneumonia
- Treatment Duration: Guides appropriate antibiotic duration
Modified PSI
- Simplified Versions: Reduced variable sets for easier calculation
- Age-Adjusted: Modified weighting for elderly populations
- Comorbidity Updates: Incorporation of newer chronic conditions
Key Clinical Pearls
- Low-Risk Confirmation: PSI Classes I-III have <1% mortality and can generally be treated as outpatients
- Social Considerations: Always assess home support, adherence capability, and follow-up access
- Dynamic Assessment: Re-evaluate patients as clinical condition evolves
- Complementary Tools: Use with CURB-65 for rapid assessment in emergency settings
- Quality Indicator: PSI-appropriate site of care is a recognized quality metric
The PSI/PORT Score remains the most comprehensively validated tool for pneumonia severity assessment and continues to guide evidence-based management decisions in community-acquired pneumonia nearly three decades after its development.
