PSI/PORT Score (Pneumonia Severity Index)
Risk stratification for community-acquired pneumonia (CAP). Superior to CURB-65 for identifying low-risk patients suitable for outpatient management.
Demographics
Comorbidities
Physical Exam Findings
Labs / Imaging
Disclaimer: For educational purposes only. Not a substitute for clinical judgment.
About This Tool
What Is the PSI/PORT Score?
The Pneumonia Severity Index (PSI), derived from the Pneumonia Patient Outcomes Research Team (PORT) cohort study, is a validated clinical prediction rule for 30-day mortality in community-acquired pneumonia. Unlike CURB-65, which relies on 5 simple variables, PSI incorporates 20 variables including demographics, comorbidities, vitals, and labs. This makes it more cumbersome to calculate manually but significantly more accurate at discriminating low-risk patients.
Why Use PSI over CURB-65?
The 2019 ATS/IDSA guidelines prefer PSI over CURB-65 for determining the site of care (outpatient vs inpatient). PSI identifies a larger proportion of low-risk patients who can be safely treated as outpatients, potentially reducing unnecessary hospital admissions. CURB-65 is easier to remember but may overestimate risk in elderly patients.
🔑 Clinical Pearls
- Age is a major driver of the score (Points = Age in years). This reflects the strong association between age and pneumonia mortality.
- Women get a -10 point adjustment, reflecting lower risk compared to age-matched men.
- The score heavily weights physiologic derangement (pH < 7.35 is +30 points).
- Don't overlook "social admission" needs — a Class I patient who cannot take oral meds or lacks home support still needs admission.
Formula last verified: February 2026