CURB-65 Score Calculator
Score the five CURB-65 criteria in community-acquired pneumonia to see the mortality band that guides the admission decision.
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What CURB-65 Does
CURB-65 is a severity score for community-acquired pneumonia, derived from the British Thoracic Society’s core adverse prognostic features. It exists to answer one practical question: can this patient be managed at home, or do they need admission — and if admitted, how urgently? Each of the five items scores one point, giving a total from 0 to 5.
The Five Criteria
- C — new onset confusion
- U — urea above 7 mmol/L (blood urea nitrogen above 19 mg/dL)
- R — respiratory rate 30 breaths per minute or more
- B — systolic blood pressure below 90 mmHg, or diastolic 60 mmHg or less
- 65 — age 65 years or older
The closely related CRB-65 drops the urea measurement, which makes it usable in primary care where blood tests are not immediately available; a score of 0 there supports outpatient management, 1–2 suggests hospital referral, and 3–4 urgent admission.
Mortality Bands
- 0–1: low risk — roughly 1.5 % 30-day mortality; outpatient care usually appropriate if the patient is stable and follow-up is arranged
- 2: moderate risk — roughly 9 % — short inpatient admission or closely supervised outpatient care
- 3–5: high risk — roughly 22 % — inpatient management, with assessment for intensive care at 4 or 5
Those percentages come from the original derivation and validation cohorts. They describe groups, not individuals, and they should never overrule clinical judgement: a young patient with a score of 1 who is hypoxic, or an older patient with a score of 2 who is deteriorating, both need more than the number suggests.
What CURB-65 Does Not Capture
- Oxygenation. Hypoxaemia is a major determinant of admission and is not part of the score; measure saturations in every patient.
- Comorbidity and frailty. Severe COPD, heart failure, immunosuppression and nursing-home residence all raise risk independently.
- Social circumstances. Living alone, poor access to care and inability to take oral medication matter as much as physiology.
- Intensive care criteria. The IDSA/ATS major and minor criteria are used for ICU decisions rather than CURB-65 alone.
- Hospital-acquired pneumonia and aspiration events, which were not part of the derivation population.
Frequently Asked Questions
What CURB-65 score requires admission?
A score of 3 or more is conventionally treated as high risk and requiring admission, and a score of 2 is a judgement call that often leads to a short admission. Oxygenation, comorbidity and social factors can all change the decision either way.
Why is urea included rather than creatinine?
Because urea rises with dehydration and the acute-phase response as well as with renal impairment, which made it a stronger predictor in the derivation data. Creatinine is used in other severity tools such as the pneumonia severity index.
Is CURB-65 the same as PSI?
No. The Pneumonia Severity Index uses around 20 variables and stratifies into five classes, while CURB-65 uses five items and is far quicker at the bedside. They perform similarly overall, with PSI better at identifying very low-risk patients.