Emergency Medicine
CURB-65 Score
Severity and mortality risk in community-acquired pneumonia.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
CURB-65 predicts 30-day mortality in community-acquired pneumonia (CAP) and helps decide whether a patient can be managed at home or needs hospital admission. One point is given for each of: Confusion (new disorientation, or an Abbreviated Mental Test score ≤8), Urea >7 mmol/L, Respiratory rate ≥30/min, low Blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg) and age ≥65 — a maximum of 5. A simplified version, CRB-65, omits urea so it can be used in the community without blood tests.
Interpreting the result
Mortality climbs steeply with the score. A score of 0–1 indicates low mortality (roughly under 3%) and many such patients can be treated at home; 2 is intermediate (around 9%) and usually warrants hospital assessment or short-stay admission; 3–5 indicates high mortality (about 15–40%) and patients should be admitted, with assessment for high-dependency or intensive care.
Advice
Score 0–1 low mortality (often manageable in the community); 2 intermediate; 3–5 high — consider hospital/critical care. Interpret with clinical judgement and social factors.
Worked example
A 70-year-old presents confused, with a respiratory rate of 32/min, urea of 9 mmol/L and blood pressure 100/70: Confusion (1) + Urea (1) + Respiratory rate (1) + Age ≥65 (1) = 4. This is a high-mortality group — admit and assess for critical-care input.
Pearls / pitfalls
- It is a mortality predictor, not a stand-alone admission rule — hypoxia, significant comorbidity or adverse social circumstances can justify admission even at a low score.
- Use CRB-65 when bloods are not available (e.g. in the community); it drops the urea criterion.
- It does not include oxygen saturation, so always assess oxygenation separately.
- Confusion means new confusion attributable to the acute illness, not long-standing cognitive impairment.
Evidence & validation
Derived and validated by Lim et al. for the British Thoracic Society and reproduced in many subsequent cohorts; endorsed by BTS and NICE for severity assessment in CAP, always alongside clinical judgement.
Frequently asked questions
What is the difference between CURB-65 and CRB-65?
CRB-65 omits the urea (blood) criterion so it can be used in the community without tests. CURB-65 adds urea >7 mmol/L and is used where bloods are available.
Does CURB-65 decide who needs intensive care?
Not directly. A score of 3–5 flags high mortality and should prompt assessment for high-dependency/intensive care, but ICU decisions use additional criteria and clinical judgement.
Can a low score be managed at home?
Often, yes — a score of 0–1 supports home treatment, but only after considering oxygen levels, comorbidities and social factors, which can override the score.
What urea threshold is used?
A serum urea greater than 7 mmol/L scores one point.
Does it account for oxygen levels?
No. CURB-65 does not include oxygen saturation, so hypoxia must be assessed and acted on independently of the score.
References
- Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study (CURB-65). Thorax. 2003;58(5):377–382.
- British Thoracic Society. Guidelines for the management of community acquired pneumonia in adults.
- NICE NG138: Pneumonia (community-acquired): antimicrobial prescribing. 2019.
About the creator
Lim WS et al.
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