The PSI was developed by Fine and colleagues in 1997 from over 50,000 patients. It is better than CURB-65 at identifying low-risk patients who can be safely treated at home. Classes I–III are low risk, IV moderate and V high.
How to use the Pneumonia Severity Index Calculator
- Sex
- Age
- Nursing home resident
- Neoplastic disease
- Liver disease
- Congestive heart failure
- Cerebrovascular disease
- Renal disease
- Altered mental status
- Respiratory rate ≥ 30/min
- Systolic BP < 90 mmHg
- Temperature < 35 °C or ≥ 40 °C
- Pulse ≥ 125/min
- Arterial pH < 7.35
- BUN ≥ 30 mg/dL (urea ≥ 11 mmol/L)
- Sodium < 130 mmol/L
- Glucose ≥ 250 mg/dL (14 mmol/L)
- Haematocrit < 30%
- PaO₂ < 60 mmHg or SaO₂ < 90%
- Pleural effusion
Results update as you type, and every field accepts the units shown in its menu.
How it works
Each answer carries the points shown in the published score. The calculator adds them up and maps the total to the published interpretation.
Scoring table
| Item | Answers and points |
|---|---|
| Sex | Male = 1; Female = 0 |
| Nursing home resident | No = 0; Yes = 10 |
| Neoplastic disease | No = 0; Yes = 30 |
| Liver disease | No = 0; Yes = 20 |
| Congestive heart failure | No = 0; Yes = 10 |
| Cerebrovascular disease | No = 0; Yes = 10 |
| Renal disease | No = 0; Yes = 10 |
| Altered mental status | No = 0; Yes = 20 |
| Respiratory rate ≥ 30/min | No = 0; Yes = 20 |
| Systolic BP < 90 mmHg | No = 0; Yes = 20 |
| Temperature < 35 °C or ≥ 40 °C | No = 0; Yes = 15 |
| Pulse ≥ 125/min | No = 0; Yes = 10 |
| Arterial pH < 7.35 | No = 0; Yes = 30 |
| BUN ≥ 30 mg/dL (urea ≥ 11 mmol/L) | No = 0; Yes = 20 |
| Sodium < 130 mmol/L | No = 0; Yes = 20 |
| Glucose ≥ 250 mg/dL (14 mmol/L) | No = 0; Yes = 10 |
| Haematocrit < 30% | No = 0; Yes = 10 |
| PaO₂ < 60 mmHg or SaO₂ < 90% | No = 0; Yes = 10 |
| Pleural effusion | No = 0; Yes = 10 |
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Age | In years |
| Nursing home resident | Choose one: No, Yes |
| Neoplastic disease | Choose one: No, Yes |
| Liver disease | Choose one: No, Yes |
| Congestive heart failure | Choose one: No, Yes |
| Cerebrovascular disease | Choose one: No, Yes |
| Renal disease | Choose one: No, Yes |
| Altered mental status | Choose one: No, Yes |
| Respiratory rate ≥ 30/min | Choose one: No, Yes |
| Systolic BP < 90 mmHg | Choose one: No, Yes |
| Temperature < 35 °C or ≥ 40 °C | Choose one: No, Yes |
| Pulse ≥ 125/min | Choose one: No, Yes |
| Arterial pH < 7.35 | Choose one: No, Yes |
| BUN ≥ 30 mg/dL (urea ≥ 11 mmol/L) | Choose one: No, Yes |
| Sodium < 130 mmol/L | Choose one: No, Yes |
| Glucose ≥ 250 mg/dL (14 mmol/L) | Choose one: No, Yes |
| Haematocrit < 30% | Choose one: No, Yes |
| PaO₂ < 60 mmHg or SaO₂ < 90% | Choose one: No, Yes |
| Pleural effusion | Choose one: No, Yes |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Score = age (minus 10 for women) + points for each finding
Class I: under 50 with none of the comorbidities or examination findings
Class II ≤ 70 · III 71–90 · IV 91–130 · V > 130
Worked example
Inputs — Sex: Male; Age: 70 years; Nursing home resident: No; Neoplastic disease: No; Liver disease: No; Congestive heart failure: No; Cerebrovascular disease: No; Renal disease: No; Altered mental status: No; Respiratory rate ≥ 30/min: No; Systolic BP < 90 mmHg: No; Temperature < 35 °C or ≥ 40 °C: No; Pulse ≥ 125/min: No; Arterial pH < 7.35: No; BUN ≥ 30 mg/dL (urea ≥ 11 mmol/L): Yes; Sodium < 130 mmol/L: No; Glucose ≥ 250 mg/dL (14 mmol/L): No; Haematocrit < 30%: No; PaO₂ < 60 mmHg or SaO₂ < 90%: No; Pleural effusion: No.
Results — PSI score = 90 points; PSI class and 30-day mortality = Class III (0.9–2.8%) – outpatient or brief observation.
Key terms
- PORT
- Pneumonia Patient Outcomes Research Team.
Frequently asked questions
How is PSI different from CURB-65?
PSI uses more variables and is better at identifying low-risk patients.
Who is class I?
Patients under 50 with no comorbidities and no abnormal vital signs or mental status.
Does PSI include oxygen levels?
Yes – but always admit patients with low oxygen regardless of class.