Community-acquired pneumonia severity

What it is and when to use it

The CURB-65 score estimates the severity of community-acquired pneumonia (CAP) and guides the decision between outpatient treatment, hospital admission, or assessment for intensive care. It assigns one point to each of five items: new-onset confusion, urea >7 mmol/L (BUN >19 mg/dL), respiratory rate ≥30/min, low blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg), and age ≥65 years. It is a stratification tool recommended by the British Thoracic Society (BTS); the ATS/IDSA CAP guideline, by contrast, preferentially recommends the Pneumonia Severity Index (PSI) for the admission decision.

How to interpret it

The score ranges from 0 to 5 and correlates with increasing 30-day mortality. A score of 0-1 indicates low risk and usually allows outpatient treatment. A score of 2 indicates intermediate risk and suggests considering hospital admission or close observation. A score of 3-5 indicates high risk, generally warranting admission, and with 4-5 points intensive care unit assessment should be considered. The CRB-65 variant, which omits urea, is useful in primary care when laboratory testing is unavailable.

Limitations and when not to use it

It was validated in adults with community-acquired pneumonia and does not apply to hospital-acquired or ventilator-associated pneumonia or to immunocompromised patients. It is a decision aid, not a substitute for clinical judgement: it may underestimate risk in young patients without comorbidities who are already severely ill, and it does not account for hypoxaemia, radiographic extent, decompensated comorbidities, or social support. It does not assess oxygenation (SpO₂/PaO₂), which is why it is often complemented with oxygen saturation and additional criteria.

Frequently asked questions

What is the difference between CURB-65 and CRB-65?

CRB-65 omits urea and scores from 0 to 4; it is intended for primary care or settings without immediate bloodwork. CURB-65 includes urea and is more common in hospital emergency departments.

What CURB-65 score requires hospital admission?

A score of 2 prompts consideration of admission or observation, and 3 or more generally indicates admission; with 4-5 points the intensive care unit should be considered.

Can CURB-65 be used to decide ICU admission?

It offers guidance (scores of 4-5 indicate high risk) but was not specifically designed for that decision; the ATS/IDSA major and minor criteria are used for ICU triage.