PSI/PORT Score Calculator

The Pneumonia Severity Index (PSI), also known as the PORT Score, stratifies 30-day mortality risk in patients with community-acquired pneumonia (CAP) to guide site-of-care decisions.

Important Clinical Disclaimer: The PSI/PORT Score is intended for use by qualified healthcare professionals only. It is for educational and informational purposes and should not replace clinical judgement. Always interpret results alongside the full clinical picture and follow your local guidelines and protocols.
PSI/PORT Assessment
Step 1: First, check if the patient qualifies for Risk Class I (lowest risk) without scoring.
Risk Class I Criteria

If ALL of the following are true, the patient is Risk Class I and does not need further scoring:

Step 2: If the patient does not meet Risk Class I criteria, complete the full scoring below.
Demographics
Points = Age (male) or Age - 10 (female)
Coexisting Conditions
Physical Examination Findings
Laboratory & Radiographic Findings
About the PSI

The Pneumonia Severity Index (PSI), developed by Fine et al. as part of the PORT study, is a validated prediction rule for 30-day mortality in community-acquired pneumonia.

Key Features:
  • Derived from over 14,000 patients
  • Validated in multiple cohorts internationally
  • Stratifies patients into 5 risk classes
  • Referenced in NICE and BTS guidelines
Use in Practice:
  • Risk Classes I-II: Consider outpatient treatment
  • Risk Class III: Consider brief observation
  • Risk Classes IV-V: Inpatient treatment

PSI Risk Class Interpretation

Risk Class PSI Score 30-Day Mortality Recommended Management
Class I Algorithm* 0.1-0.4% Outpatient treatment
Class II ≤70 0.6-0.7% Outpatient treatment
Class III 71-90 0.9-2.8% Brief inpatient observation or outpatient with close follow-up
Class IV 91-130 8.2-9.3% Inpatient treatment
Class V >130 27.0-31.1% Inpatient treatment (consider ICU)

*Class I is determined by the initial algorithm (age ≤50, no comorbidities, normal vital signs/mental status) without need for scoring.

Clinical Considerations:
  • The PSI may underestimate severity in younger patients without comorbidities
  • Consider using CURB-65 alongside PSI for a more complete assessment
  • Social factors (ability to take oral medications, home support) must be considered
  • Clinical judgement should override the score if there are concerns

Limitations

PSI Limitations
  • Complexity - requires multiple data points including laboratory values
  • Age-weighted - older patients score higher regardless of severity
  • May underestimate risk in young, otherwise healthy patients
  • Does not account for multilobar disease, virulence of organism
  • Not validated for immunocompromised patients, hospital-acquired pneumonia, or aspiration pneumonia
Important Notes
  • Social factors - ability to take oral medication, adequate home support
  • Comorbidity definitions must be applied correctly
  • Laboratory values may not be available in all settings
  • Consider CURB-65 as a simpler alternative in some settings
  • Follow local guidelines - BTS and NICE may have specific recommendations

Coexisting Condition Definitions

Condition Definition
Neoplastic disease Any cancer except basal or squamous cell skin cancer, active at time of presentation or diagnosed within 1 year
Liver disease Clinical or histological diagnosis of cirrhosis, or other forms of chronic liver disease (e.g., chronic active hepatitis)
Congestive heart failure Documented by history, physical examination, chest X-ray, echocardiography, or other imaging
Cerebrovascular disease History of stroke or TIA, or known cerebrovascular disease documented by imaging
Renal disease History of chronic renal disease or abnormal creatinine/BUN documented in medical record

Frequently Asked Questions

They are the same scoring system. PSI stands for Pneumonia Severity Index, while PORT refers to the Pneumonia Patient Outcomes Research Team study that derived and validated the score. Both names are used interchangeably in clinical practice.

Both are validated tools with different strengths:

  • PSI/PORT - More comprehensive, better validated for identifying low-risk patients suitable for outpatient treatment, but requires laboratory values
  • CURB-65 - Simpler (5 variables), can be calculated without laboratory data (CRB-65), may better identify high-risk patients

BTS guidelines suggest using CURB-65 as the primary tool, while considering PSI for identifying low-risk patients. Many clinicians use both complementarily.

Yes. The PSI is age-weighted, meaning younger patients start with fewer points. A young patient without comorbidities may have a low PSI score despite severe pneumonia. Always consider:

  • Clinical appearance and trajectory
  • Respiratory rate and oxygen requirements
  • Ability to tolerate oral intake
  • Social circumstances and ability to monitor at home

Clinical judgement must always take precedence over any scoring system.

If laboratory values are not available:

  • Use CURB-65 or CRB-65 (which doesn't require bloods) as an alternative
  • If using PSI, assume normal values for missing data (this may underestimate severity)
  • Consider whether bloods should be obtained based on clinical assessment

In primary care or community settings, CRB-65 is often more practical.

NICE guideline NG138 (Pneumonia in adults) recommends:

  • Use CRB-65 in primary care (no laboratory values needed)
  • Use CURB-65 in hospital settings
  • Consider PSI to identify patients at low risk who may be suitable for outpatient management
  • Always use clinical judgement alongside severity scores

BTS guidelines similarly endorse CURB-65 as the primary tool in the UK.

Disclaimer

This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

  • Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition.
  • Never disregard professional medical advice or delay seeking it because of information from this tool.
  • Clinical decision-making should always incorporate the full clinical context, patient preferences, and local protocols.
  • The creators of this tool accept no liability for decisions made based on its output.

If you are a patient: please discuss any results with your healthcare provider. This tool is designed for use by medical professionals and may not be appropriate for self-assessment.

References

  1. Fine MJ, et al. (1997). A prediction rule to identify low-risk patients with community-acquired pneumonia. New England Journal of Medicine, 336(4), 243-250.
  2. Fine MJ, et al. (1999). Prognosis and outcomes of patients with community-acquired pneumonia. A meta-analysis. JAMA, 275(2), 134-141.
  3. British Thoracic Society (2015). BTS Guidelines for the management of community acquired pneumonia in adults.
  4. NICE (2019). Pneumonia (community-acquired): antimicrobial prescribing (NG138). National Institute for Health and Care Excellence.
  5. Aujesky D, et al. (2005). Prospective comparison of three validated prediction rules for prognosis in community-acquired pneumonia. American Journal of Medicine, 118(4), 384-392.