Medical AICURB-65 pneumonia severity calculator
Five equally-weighted criteria score community-acquired pneumonia severity from 0 to 5, stratifying 30-day mortality risk and informing whether a patient can be managed as an outpatient or needs admission.
How to measure each input
- Confusion
- Assess for new disorientation. The original derivation used an Abbreviated Mental Test score of 8 or less; new confusion relative to baseline is the practical bedside equivalent.
- Urea / BUN
- Use serum urea > 7 mmol/L. If your lab reports blood urea nitrogen, the equivalent threshold is > 19 mg/dL (BUN mg/dL is roughly urea mmol/L times 2.8).
- Respiratory rate
- Count respirations over a full minute at rest; brief 15-second counts overestimate at the high end.
- Blood pressure
- Either component triggers the point: systolic < 90 mmHg or diastolic <= 60 mmHg.
- Age
- Chronological age 65 years or older. This is the single most heavily weighted demographic factor.
Interpretation
| Band | Meaning |
|---|---|
| 0 to 1, low severity | Low 30-day mortality (around 1.5%). Outpatient management is usually appropriate when social circumstances allow. |
| 2, moderate severity | Intermediate 30-day mortality (around 9%). Consider a short inpatient stay or closely supervised outpatient care. |
| 3 to 5, high severity | High 30-day mortality (around 22% or more). Admit and assess for intensive-care or high-dependency support, especially at 4 to 5. |
Pitfalls, exclusions and caveats
- CURB-65 estimates mortality risk; it does not by itself decide disposition. Hypoxia, decompensated comorbidity, and social factors can warrant admission at a low score.
- It was derived and validated in adults; do not apply it to children.
- The simplified CRB-65 (omitting urea) exists for settings without immediate bloods, but uses different thresholds and bands.
- A normal score does not exclude severe pneumonia in the immunocompromised, in early presentation, or where oxygenation is the dominant concern.
- Pregnancy, recent immunosuppression, and aspiration physiology are not captured and need separate judgement.
1 point each: Confusion + Urea > 7 mmol/L (BUN > 19 mg/dL) + Respiratory rate >= 30 + (SBP < 90 mmHg or DBP <= 60 mmHg) + Age >= 65. Total 0 to 5.CURB-65 was derived by Lim et al. (2003). This implementation is an educational tool and is not affiliated with the original authors or any guideline body.
Frequently asked
What CURB-65 score means a patient can go home?
A score of 0 to 1 carries low 30-day mortality and patients can often be managed as outpatients, provided oxygenation, comorbidity, and social circumstances are acceptable. The score informs, but does not replace, that judgement.
What is the urea threshold in mg/dL?
The criterion is serum urea > 7 mmol/L, which corresponds to blood urea nitrogen (BUN) > 19 mg/dL. One point is added when either is exceeded.
How does CURB-65 differ from CRB-65?
CRB-65 drops the urea criterion so it can be used without blood tests, for example in primary care. It scores 0 to 4 and uses its own risk bands, so the two should not be read interchangeably.
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