How CURB-65 is calculated
CURB-65 is a 5-point additive score for community-acquired pneumonia severity. One point is scored for each criterion present.
| Letter | Criterion |
|---|---|
| C | Confusion (new disorientation to person, place, or time) |
| U | Urea > 7 mmol/L (≈ BUN > 19–20 mg/dL) |
| R | Respiratory rate ≥ 30/min |
| B | Blood pressure: systolic < 90 mmHg or diastolic ≤ 60 mmHg |
| 65 | Age ≥ 65 years |
Normal values & risk bands
| Score | 30-day mortality | Suggested disposition |
|---|---|---|
| 0 – 1 | ~1.5% | Likely outpatient treatment |
| 2 | ~9.2% | Consider short inpatient stay |
| 3 | ~22% | Inpatient, consider ICU |
| 4 – 5 | ~40%+ | ICU-level care |
Clinical use
CURB-65 helps decide whether a patient with community-acquired pneumonia can be safely treated as an outpatient or needs admission (and at what level of care). It should support, not replace, clinical judgement — factors like oxygen saturation, comorbidities, social circumstances, and ability to take oral medication also matter. The CRB-65 variant (omitting urea) is used where a blood test isn't immediately available, e.g. in primary care.
Frequently asked questions
What is the CURB-65 score used for?
It estimates mortality risk in community-acquired pneumonia and helps decide whether a patient can be safely managed as an outpatient or needs hospital admission.
What does a CURB-65 score of 2 mean?
A score of 2 indicates moderate risk (roughly 9% 30-day mortality) and typically prompts consideration of a short inpatient admission, rather than outright outpatient treatment.
What's the difference between CURB-65 and CRB-65?
CRB-65 drops the urea ("U") criterion, making it usable without a blood test — useful in primary care or settings without rapid lab access. CURB-65 (with urea) is used once labs are available, typically in hospital.
Does CURB-65 replace clinical judgement?
No — it's a decision-support tool. Factors it doesn't capture (oxygen saturation, comorbidities, ability to take oral treatment, social circumstances) still need to be weighed alongside the score.
References
- Lim WS, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58:377–382.
- British Thoracic Society Guidelines for the management of community acquired pneumonia in adults. Thorax. 2009;64(Suppl III).