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PSI (Pneumonia Severity Index) — Free Online Calculator

Demographics

years

Comorbidities

Physical Exam

Laboratory / Imaging

PSI / PORT Score

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About This Calculator

The Pneumonia Severity Index (PSI), also known as the PORT score, stratifies community-acquired pneumonia patients into risk classes to guide disposition decisions (outpatient vs. inpatient vs. ICU). It uses 20 variables including demographics, comorbidities, physical exam findings, and laboratory results. PSI is validated for predicting 30-day mortality and helps identify low-risk patients who can be safely treated as outpatients.

Formula

PSI Score = Age (years, minus 10 if female) + Comorbidity Points + Physical Exam Points + Lab Points
Class I: Age <50, no comorbidities, normal vitals → outpatient
Class II: ≤70 | Class III: 71-90 | Class IV: 91-130 | Class V: >130

Interpretation

PSI ClassScoreMortalityDisposition
I – II≤ 700.1–0.7%Outpatient
III71 – 900.9–2.8%Observation / outpatient
IV91 – 1308.2–9.3%Inpatient
V> 13027–31%ICU consideration

References

  1. Fine MJ, et al. A prediction rule to identify low-risk patients with community-acquired pneumonia. N Engl J Med. 1997;336(4):243-250.
  2. Aujesky D, et al. Prospective comparison of three validated prediction rules for prognosis in community-acquired pneumonia. Am J Med. 2005;118(4):384-392.

Frequently Asked Questions

How does PSI compare to CURB-65?

PSI/PORT is more complex (20 variables) but better at identifying low-risk patients for outpatient treatment. CURB-65 is simpler (5 variables) and better at identifying high-risk patients needing ICU. Many guidelines recommend using both in complementary fashion.

Can PSI Class I be determined without lab work?

Yes. Patients under 50 with no comorbidities (neoplasm, liver disease, CHF, cerebrovascular disease, renal disease) and normal vitals/mental status are Class I regardless of lab results. This allows rapid identification of very low-risk patients in the ED.

Does PSI account for social factors?

No. PSI is a mortality prediction tool, not a comprehensive disposition tool. Social factors (homelessness, inability to take oral medications, substance abuse, lack of follow-up) may warrant admission even for low PSI classes. Clinical judgment should supplement the score.

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⚠ Medical Disclaimer

This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.