🫁 PSI / PORT Pneumonia Severity Index
Pneumonia Severity Index (PSI/PORT), a 20-variable score stratifying community-acquired pneumonia 30-day mortality into classes I–V.
PSI identifies low-risk patients (classes I–III) who can often be treated as outpatients, reducing unnecessary admissions (original synthesis · not guideline verbatim).
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When to use
Use to risk-stratify CAP and inform outpatient vs inpatient disposition, preferred by 2019 ATS/IDSA over CURB-65.
How it works
Points from age (minus 10 if female), nursing-home residence, five comorbidities, five exam findings, and seven lab/imaging findings; class I requires age ≤ 50 with no comorbidity/exam abnormality, then II ≤ 70, III 71–90, IV 91–130, V ≥ 131.
Key points
- PSI identifies low-risk patients (classes I–III) who can often be treated as outpatients, reducing unnecessary admissions (original synthesis · not guideline verbatim).
- It is more discriminating than CURB-65 but more complex, requiring labs and arterial gas variables.
- Override the score with clinical judgment for hypoxemia, unstable comorbidity, or social barriers to outpatient care.
References
- Fine MJ, et al. PSI derivation. N Engl J Med 1997.
- Metlay JP, et al. ATS/IDSA CAP guideline. Am J Respir Crit Care Med 2019.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Age | 65 yr |
|---|---|
| Sex | Male |
| Nursing-home resident | Yes |
| History of neoplasm | Yes |
| History of liver disease | Yes |
| History of congestive heart failure | Yes |
| History of cerebrovascular disease | Yes |
| History of renal disease | Yes |
| Altered mental status | Yes |
| Respiratory rate ≥ 30/min | Yes |
| Systolic BP < 90 mmHg | Yes |
| Temperature < 35℃ or ≥ 40℃ | Yes |
| Pulse ≥ 125/min | Yes |
| Arterial pH < 7.35 | Yes |
| BUN ≥ 30 mg/dL (urea ≥ 10.7 mmol/L) | Yes |
| Sodium < 130 mmol/L | Yes |
| Glucose ≥ 250 mg/dL (≥ 13.9 mmol/L) | Yes |
| Hematocrit < 30% | Yes |
| PaO₂ < 60 mmHg | Yes |
| Pleural effusion | Yes |
→PSI risk classClass V
- Total score：350 pts
- 30-day mortality (approx.)：27–31%
- Disposition reference：Inpatient (consider ICU)
| Age | 65 yr |
|---|---|
| Sex | Female |
| Nursing-home resident | No |
| History of neoplasm | No |
| History of liver disease | No |
| History of congestive heart failure | No |
| History of cerebrovascular disease | No |
| History of renal disease | No |
| Altered mental status | No |
| Respiratory rate ≥ 30/min | No |
| Systolic BP < 90 mmHg | No |
| Temperature < 35℃ or ≥ 40℃ | No |
| Pulse ≥ 125/min | No |
| Arterial pH < 7.35 | No |
| BUN ≥ 30 mg/dL (urea ≥ 10.7 mmol/L) | No |
| Sodium < 130 mmol/L | No |
| Glucose ≥ 250 mg/dL (≥ 13.9 mmol/L) | No |
| Hematocrit < 30% | No |
| PaO₂ < 60 mmHg | No |
| Pleural effusion | No |
→PSI risk classClass II
- Total score：55 pts
- 30-day mortality (approx.)：0.6%
- Disposition reference：Outpatient
Frequently asked questions
- What is PSI / PORT Pneumonia Severity Index?
- Pneumonia Severity Index (PSI/PORT), a 20-variable score stratifying community-acquired pneumonia 30-day mortality into classes I–V.
- How is PSI / PORT Pneumonia Severity Index calculated? What is the core formula?
- Points from age (minus 10 if female), nursing-home residence, five comorbidities, five exam findings, and seven lab/imaging findings; class I requires age ≤ 50 with no comorbidity/exam abnormality, then II ≤ 70, III 71–90, IV 91–130, V ≥ 131.
- When is PSI / PORT Pneumonia Severity Index used?
- Use to risk-stratify CAP and inform outpatient vs inpatient disposition, preferred by 2019 ATS/IDSA over CURB-65.
- What are the key clinical points for PSI / PORT Pneumonia Severity Index?
- PSI identifies low-risk patients (classes I–III) who can often be treated as outpatients, reducing unnecessary admissions (original synthesis · not guideline verbatim). It is more discriminating than CURB-65 but more complex, requiring labs and arterial gas variables. Override the score with clinical judgment for hypoxemia, unstable comorbidity, or social barriers to outpatient care.
- What are the limits and cautions when using PSI / PORT Pneumonia Severity Index?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is PSI / PORT Pneumonia Severity Index calculated in practice? Can you show a worked example?
- Inputs: Age 65 yr, Sex Male, Nursing-home resident Yes, History of neoplasm Yes, History of liver disease Yes, History of congestive heart failure Yes, History of cerebrovascular disease Yes, History of renal disease Yes… → Result: PSI risk class Class V（Total score: 350 pts, 30-day mortality (approx.): 27–31%, Disposition reference: Inpatient (consider ICU)） Inputs: Age 65 yr, Sex Female, Nursing-home resident No, History of neoplasm No, History of liver disease No, History of congestive heart failure No, History of cerebrovascular disease No, History of renal disease No… → Result: PSI risk class Class II（Total score: 55 pts, 30-day mortality (approx.): 0.6%, Disposition reference: Outpatient）