Pneumonia Severity Index (PSI/PORT) Score Calculator

What Is the Pneumonia Severity Index (PSI / PORT Score)?

The Pneumonia Severity Index (PSI), also known as the PORT (Pneumonia Patient Outcomes Research Team) score, is a clinical prediction rule used by medical professionals to estimate 30-day mortality risk in adult patients diagnosed with community-acquired pneumonia (CAP). By evaluating demographics, pre-existing comorbidities, physical examination vitals, and laboratory and radiographic findings, the PSI categorizes patients into five distinct risk classes to assist in deciding whether outpatient therapy, short-stay observation, or full hospital admission is appropriate.

How the Pneumonia Severity Index Is Calculated

The PSI utilizes a two-step scoring algorithm designed to quickly identify very low risk patients first, followed by point-based stratification for remaining individuals:

Step 1: Low-Risk Rule (Risk Class I) - Adult patients aged 50 years or younger with no history of neoplastic disease, liver disease, congestive heart failure, cerebrovascular disease, or renal disease, who demonstrate completely normal mental status and stable vital signs, are assigned directly to Risk Class I without requiring extensive laboratory workup.
Step 2: Point Scoring System (Risk Classes II through V) - For patients over 50 years of age or those with underlying conditions or abnormal vitals, points are added across four distinct domains:

1. Demographic Factors

Age for Males: Age in years (for example, a 68-year-old male receives 68 points).
Age for Females: Age in years minus 10 points (for example, a 68-year-old female receives 58 points).
Nursing Home Resident: +10 points.

2. Co-existing Medical Conditions

Neoplastic Disease (Active Cancer): +30 points.
Liver Disease: +20 points.
Congestive Heart Failure: +10 points.
Cerebrovascular Disease (Stroke / TIA): +10 points.
Renal Disease (Chronic Kidney Disease): +10 points.

3. Physical Examination Findings

Altered Mental Status (Acute Disorientation / Lethargy): +20 points.
Respiratory Rate ≥ 30 breaths/min: +20 points.
Systolic Blood Pressure < 90 mmHg: +20 points.
Temperature < 35°C (95°F) or ≥ 40°C (104°F): +15 points.
Pulse ≥ 125 beats/min: +10 points.

4. Laboratory and Radiographic Findings

Arterial pH < 7.35: +30 points.
Blood Urea Nitrogen (BUN) ≥ 30 mg/dL (10.7 mmol/L): +20 points.
Serum Sodium < 130 mEq/L (mmol/L): +20 points.
Serum Glucose ≥ 250 mg/dL (14 mmol/L): +10 points.
Hematocrit < 30%: +10 points.
Partial Pressure of Arterial Oxygen (PaO&sub2;) < 60 mmHg or SpO&sub2; < 90%: +10 points.
Pleural Effusion on Chest Radiograph: +10 points.

Risk Classification and Mortality Rates

Risk Class	PSI Score	Risk Level	30-Day Mortality	Recommended Treatment Site
Class I	≤ 50 (Age ≤ 50 + no risk factors)	Low Risk	0.1%	Outpatient management
Class II	≤ 70 points	Low Risk	0.6%	Outpatient management
Class III	71 to 90 points	Low-to-Moderate Risk	2.8%	Outpatient or short-stay observation unit
Class IV	91 to 130 points	Moderate Risk	8.2%	Inpatient hospitalization
Class V	> 130 points	High Risk	29.2%	Inpatient hospitalization (evaluate for ICU)

PSI Score vs. CURB-65 Score

Both the Pneumonia Severity Index and the CURB-65 Calculator are recommended in international infectious disease guidelines (such as ATS/IDSA). While CURB-65 is brief and uses five easily memorable variables, the PSI incorporates a broader set of 20 clinical, laboratory, and radiographic parameters. Clinical studies have shown that PSI has a higher sensitivity for identifying low-risk candidates safe for outpatient recovery, safely reducing unnecessary hospital admissions.

Frequently Asked Questions

What is the main purpose of the PSI / PORT score?

The primary purpose is to objectively stratify adult patients with community-acquired pneumonia into risk classes based on predicted 30-day mortality, assisting emergency clinicians and hospitalists in identifying patients who can safely be treated at home versus those requiring inpatient admission or intensive care.

Why do females get 10 points subtracted from their age?

Epidemiological validation studies conducted by the Pneumonia Patient Outcomes Research Team demonstrated that female patients have a statistically lower baseline mortality risk from community-acquired pneumonia compared to age-matched male patients, reflected as a 10-point adjustment.

Can a patient in Risk Class I or II still be admitted to the hospital?

Yes. Clinical judgment always supersedes score calculations. Social factors (such as lack of home support, cognitive impairment, or homelessness), inability to tolerate oral medications, severe intractable vomiting, or unstable comorbidities not captured in the score may warrant admission even in low-risk classes.

How does oxygenation affect the PSI score?

Hypoxemia defined as an arterial PaO&sub2; below 60 mmHg or an oxygen saturation (SpO&sub2;) below 90% adds 10 points to the total score. Respiratory distress or compromised gas exchange is also reflected by respiratory rate ≥ 30 breaths/min (+20 points).

Is PSI applicable to hospital-acquired or ventilator-associated pneumonia?

No. The Pneumonia Severity Index was validated exclusively for community-acquired pneumonia (CAP) in adults presenting from outpatient or emergency settings. It is not designed for hospital-acquired (HAP) or ventilator-associated pneumonia (VAP).

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Pneumonia Severity Index Calculator