The Pneumonia Severity Index (PSI) calculator is designed to evaluate the severity of pneumonia in patients by assessing various risk factors. This tool helps determine the level of care a patient may require, such as outpatient treatment or hospitalization, based on their risk classification.

The calculator uses a combination of patient demographics and health indicators to compute a PSI Score. Here’s how it works:

1. Start with the patient's age as the base score.
2. If the patient is female, subtract 10 points from the score to adjust for gender differences.
3. Additional points are added to the score based on patient health conditions and symptoms:
   - Nursing home residency: Add 10 points.
   - History of neoplastic disease: Add 30 points.
   - History of liver disease: Add 20 points.
   - History of congestive heart failure: Add 10 points.
   - History of cerebrovascular disease: Add 10 points.
   - History of renal disease: Add 10 points.
   - Altered mental status: Add 20 points.
   - Respiratory rate of 30 or more breaths per minute: Add 20 points.
   - Systolic blood pressure less than 90 mmHg: Add 20 points.
   - Temperature outside the range of 35°C to 39.9°C: Add 15 points.
   - Pulse rate of 125 or more beats per minute: Add 10 points.
   - pH less than 7.35: Add 30 points.
   - Blood urea nitrogen (BUN) of 30 mg/dL or more: Add 20 points.
   - Sodium level less than 130 mmol/L: Add 20 points.
   - Glucose level of 250 mg/dL or more: Add 10 points.
   - Hematocrit level less than 30%: Add 10 points.
   - Partial pressure of oxygen less than 60 mmHg: Add 10 points.
   - Presence of pleural effusion on an X-ray: Add 10 points.

Once the total PSI Score is calculated, it is used to categorize the patient into one of several risk classes:

- Risk Class I (Low) applies if all additional health criteria are negative, with the score being equal to the patient's age only.
- Risk Class II (Low) reflects a total PSI Score of 70 or less.
- Risk Class III (Low) corresponds to a score between 71 and 90.
- Risk Class IV (Moderate) covers scores between 91 and 130.
- Risk Class V (High) includes scores over 130.

This classification system helps medical professionals assess the severity and potential complications of pneumonia, guiding decisions about the necessary care level.

The PSI/PORT Score calculates the severity of community-acquired pneumonia (CAP) based on clinical, laboratory, and demographic factors. It helps stratify patients into risk classes for mortality, guiding decisions on outpatient vs. inpatient care.

It's not yet validated for COVID-19.

Pneumonia Severity Index for CAP (PSI/PORT Score)