Primary Care
CRB-65 Score
Community pneumonia severity (no bloods needed).
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
CRB-65 is a simplified version of CURB-65 that assesses the severity of community-acquired pneumonia using only bedside findings, with no blood tests required. One point is given for each of: Confusion (new disorientation), Respiratory rate of 30 or more per minute, low Blood pressure (systolic below 90 mmHg or diastolic 60 mmHg or below) and age 65 or over — a maximum of 4. By omitting the urea criterion of CURB-65, it can be applied in the community to help decide who needs hospital referral. It estimates the risk of death from pneumonia.
Interpreting the result
Mortality rises with the score. A score of 0 indicates low risk, where home treatment can often be considered; 1–2 is intermediate and usually warrants hospital assessment; and 3–4 is high risk, prompting urgent hospital admission. In hospital, where bloods are available, CURB-65 (which adds urea) is generally preferred. The score should always be combined with clinical judgement, oxygen saturation, comorbidity and social circumstances, any of which can override it.
Advice
In hospital, CURB-65 (which adds urea) is preferred. Use with clinical judgement and local guidance.
Worked example
A 70-year-old at home is newly confused with a respiratory rate of 32 per minute and a blood pressure of 95/60: Confusion (1) + Respiratory rate (1) + low Blood pressure — diastolic ≤60 (1) + Age 65 or over (1) = 4. This is high risk, prompting urgent hospital admission.
Pearls / pitfalls
- It is a mortality predictor, not an admission rule on its own — hypoxia, frailty, comorbidity or poor social support can justify admission even at a score of 0.
- It does not include oxygen saturation, so assess and act on oxygenation independently of the score.
- 'Confusion' means new disorientation due to the acute illness, not longstanding cognitive impairment.
- In hospital, prefer CURB-65 (which adds urea); CRB-65 is for settings without ready access to bloods.
Evidence & validation
CRB-65 derives from the CURB-65 work by Lim and colleagues for the British Thoracic Society, validated as a simpler community tool with reasonable performance for predicting mortality. It is endorsed by BTS and NICE for severity assessment in community-acquired pneumonia when blood tests are not to hand, always alongside clinical judgement.
Frequently asked questions
What is the difference between CRB-65 and CURB-65?
CRB-65 omits the urea criterion so it can be used in the community without blood tests, scoring out of 4. CURB-65 adds urea above 7 mmol/L, scoring out of 5, and is preferred in hospital.
What CRB-65 score needs hospital admission?
A score of 3–4 is high risk and warrants urgent admission, 1–2 usually warrants hospital assessment, and 0 may allow home treatment. Clinical judgement and social factors always apply.
Does CRB-65 account for oxygen levels?
No. It does not include oxygen saturation, so hypoxia must be assessed and acted on separately. A patient with a low score but low oxygen levels may still need admission.
Can a score of 0 always be treated at home?
Often, but not always. Comorbidity, frailty, hypoxia or unsafe social circumstances can override a low score and justify admission, so the number is only one part of the decision.
What counts as confusion in CRB-65?
New disorientation attributable to the acute illness, not pre-existing cognitive impairment such as established dementia. A formal mental test or a clear new change supports the criterion.
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. Thorax. 2003;58(5):377–382.
- NICE NG138: Pneumonia (community-acquired): antimicrobial prescribing. 2019.
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