CURB-65 Calculator

CURB-65 criteria

Each of the five criteria scores 1 point, giving a total from 0 to 5. The acronym maps directly onto the criteria: Confusion, Urea, Respiratory rate, Blood pressure and age 65.

CRB-65 is the same score without the urea criterion. It is used in community and primary care settings where blood results are not available, and scores 0 to 4.

CURB-65 score interpretation

The score bands below reflect 30-day mortality risk in the original derivation and validation work, and the disposition guidance that follows from it.

• 0–1Low risk (1–2% mortality)

  Consider home treatment with oral antibiotics.

• 2Moderate risk (9% mortality)

  Consider short-stay inpatient or hospital-supervised outpatient treatment.

• 3–4High risk (15–22% mortality)

  Manage as severe pneumonia. Hospital admission recommended.

• 5Very high risk (>40% mortality)

  Urgent hospital admission. Consider ICU assessment.

How to calculate CURB-65

1. 1Confirm a working diagnosis of community-acquired pneumonia — CURB-65 is not validated for hospital-acquired pneumonia or for other causes of breathlessness.
2. 2Assess for new confusion, using an abbreviated mental test if the baseline is unclear.
3. 3Check the urea result and score 1 if it is above 7 mmol/L. If no bloods are available, use CRB-65 instead.
4. 4Count the respiratory rate and record the blood pressure.
5. 5Add a point for age 65 or over, sum the criteria, and interpret alongside comorbidity, oxygenation, social circumstances and the patient wishes.

Common pitfalls

• Using CURB-65 as the sole disposition decision. It does not account for hypoxia, bilateral changes, comorbidity, immunosuppression or the ability to cope at home.
• Applying it to hospital-acquired or aspiration pneumonia, where it has not been validated.
• Scoring long-standing cognitive impairment as confusion — the criterion is new confusion.
• Reporting a CURB-65 score in the community when no urea result exists. Without urea the correct score is CRB-65.
• Under-triaging a young patient. A low score in someone with significant hypoxia or sepsis physiology still warrants admission.

Frequently asked questions

When should CURB-65 be used?

CURB-65 is used for adults with community-acquired pneumonia to assess severity and guide the decision between home treatment, hospital admission, and intensive care review. It should be used alongside clinical judgement and consideration of comorbidities and social circumstances.

How do you interpret the CURB-65 score?

A score of 0-1 is low risk (1-2% mortality) - consider home treatment with oral antibiotics. A score of 2 is moderate risk (9% mortality) - consider short-stay inpatient or hospital-supervised outpatient treatment. A score of 3-4 is high risk (15-22% mortality) - manage as severe pneumonia with hospital admission. A score of 5 is very high risk (over 40% mortality) - urgent admission with ICU assessment.

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

CRB-65 omits the urea criterion and therefore scores 0 to 4. It is designed for community and primary care settings where blood results are not available at the point of assessment.

Does CURB-65 apply to hospital-acquired pneumonia?

No. CURB-65 was derived and validated in community-acquired pneumonia. It is not validated for hospital-acquired, ventilator-associated or aspiration pneumonia.

What counts as confusion in CURB-65?

New disorientation in person, place or time, or an abbreviated mental test score of 8 or less. Chronic cognitive impairment that has not changed does not score.

Sources and further reading

• Pneumonia in adults: diagnosis and management (CG191) — NICE
• Annotated BTS guideline for the management of CAP in adults — British Thoracic Society

This page is reference information for registered healthcare professionals. It is not medical advice and does not replace clinical judgement, local policy, or the current version of the source guidance. Always verify scores and thresholds against your own organisation's pathway before acting on them.