PSI/PORT Score Calculator

PSI/PORT Score Calculator for Pulmonology. Scores stratify 30-day mortality into five classes: Class I and II (0.1 to 0.7 percent) and Class III (about 0.9 to 2.8 percent) constitute low risk. Class IV (roughly 8 to 9 percent) and Class V (about 27 to 31 percent) are high risk. The point cutoffs are: Class II up to 70, Class III 71 to 90, Class IV 91 to 130, and Class V above 130. In practice, Classes I and II support outpatient treatment, Class III often warrants brief observation or a short admission, and Classes IV and V call for hospitalization, with Class V prompting evaluation for intensive care.

How this calculator works

The Pneumonia Severity Index (PSI), derived from the Pneumonia Patient Outcomes Research Team (PORT) cohort, is a two-step additive risk model for adults with community-acquired pneumonia (CAP). Step one screens for low risk: patients under 50 with no comorbidity (neoplasm, liver disease, heart failure, cerebrovascular or renal disease) and no significant vital-sign or mental-status derangement are assigned Class I without further scoring. Everyone else accrues points across 20 weighted variables spanning demographics (age in years equals points; women subtract 10; nursing-home residence adds 10), five comorbidities, five examination findings (altered mental status, respiratory rate 30 or more, systolic BP under 90, temperature under 35 or 40 or more degrees C, pulse 125 or more), and six laboratory or radiographic findings (arterial pH under 7.35, BUN 30 mg/dL or more, sodium under 130, glucose 250 or more, hematocrit under 30 percent, PaO2 under 60 mmHg or SaO2 under 90 percent, pleural effusion). The total maps to Classes II through V.

When to use this calculator

Use the PSI in adults presenting with radiographically confirmed CAP to inform the initial site-of-care decision (outpatient versus ward versus higher-acuity monitoring). It is best validated as a rule-out tool for identifying low-risk patients who can be safely treated at home. Do not apply it to immunocompromised hosts (HIV, transplant, neutropenia), to hospital-acquired or ventilator-associated pneumonia, or as a substitute for judgment about oxygenation, ability to take oral therapy, or social barriers to outpatient care. It does not identify candidates for ICU admission.

Inputs used

  • Age
  • Sex
  • Nursing home status
  • Comorbid illnesses
  • Vital signs and mental status
  • Selected laboratory findings
  • Pleural effusion
  • Oxygenation

Clinical interpretation

Scores stratify 30-day mortality into five classes: Class I and II (0.1 to 0.7 percent) and Class III (about 0.9 to 2.8 percent) constitute low risk. Class IV (roughly 8 to 9 percent) and Class V (about 27 to 31 percent) are high risk. The point cutoffs are: Class II up to 70, Class III 71 to 90, Class IV 91 to 130, and Class V above 130. In practice, Classes I and II support outpatient treatment, Class III often warrants brief observation or a short admission, and Classes IV and V call for hospitalization, with Class V prompting evaluation for intensive care.

Worked example

A 68-year-old man with CAP: age contributes 68 points; congestive heart failure adds 10; respiratory rate of 32 adds 20; BUN of 34 mg/dL adds 20; sodium of 128 adds 20. Total equals 138 points, placing him in Risk Class V (above 130). Observed 30-day mortality for Class V in the validation cohort was roughly 27 to 31 percent, so this patient warrants inpatient admission with consideration of intensive monitoring rather than outpatient management.

Limitations and safety notes

The PSI heavily weights age and chronic comorbidity, so it can under-triage young, previously healthy patients with rapidly progressive pneumonia and physiologic instability who nonetheless score low. It requires arterial blood gas and multiple labs, making it cumbersome at initial triage compared with CURB-65. It predicts mortality, not the need for ICU-level support or vasopressors, so it should not be used alone to decide critical-care admission. Performance is not established in immunosuppressed or nursing-home populations with atypical presentations, and pregnancy is excluded.

Frequently asked questions

How does the PSI differ from CURB-65?

CURB-65 uses only five criteria (confusion, urea, respiratory rate, blood pressure, age 65 or older) and is faster at the bedside, while the PSI evaluates 20 variables and requires labs including an arterial blood gas. The PSI is more sensitive for identifying low-risk patients but is more complex; CURB-65 is simpler but can under-detect some low-risk older patients.

Does a low PSI class mean the patient definitely can go home?

No. A low class (I to III) identifies low mortality risk, but the final decision must also account for hypoxemia, inability to tolerate oral intake, unstable comorbidities, and social factors such as homelessness or inability to obtain and take medications. The score is a floor for safety, not a complete discharge checklist.

Can the PSI be used to decide ICU admission?

Not reliably. The PSI predicts 30-day mortality, not the need for mechanical ventilation or vasopressor support. Tools such as the ATS/IDSA minor criteria or SMART-COP are more appropriate for identifying candidates for intensive respiratory or vasopressor support.

Why do women subtract 10 points?

In the derivation cohort, female sex was independently associated with lower 30-day mortality after adjustment for other variables, so the model applies a 10-point reduction for women to calibrate risk accurately.

Is the PSI valid in nursing-home residents?

Nursing-home residence adds 10 points and such patients were represented in the cohorts, but the PSI was derived mainly in patients able to undergo standard workup. Frail institutionalized patients with atypical presentations or goals-of-care limits may not be well served by the score alone.

References

  • Fine MJ, Auble TE, Yealy DM, Hanusa BH, Weissfeld LA, Singer DE, Coley CM, Marrie TJ, Kapoor WN. A prediction rule to identify low-risk patients with community-acquired pneumonia. N Engl J Med. 1997. PMID: 8995086.
  • Metlay JP, Waterer GW, Long AC, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019. PMID: 31573350.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: April 12, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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