What is CURB-65?
CURB-65 is a five-point clinical prediction score used to estimate the severity of community-acquired pneumonia (CAP) and guide the decision between outpatient treatment, hospital admission, and ICU-level care. It was derived from British Thoracic Society pneumonia severity research and validated by Lim and colleagues, published in Thorax in 2003. Because each component is quick to obtain at the bedside — confusion, urea, respiratory rate, blood pressure, and age — it's widely used in emergency departments and on the wards as a rapid first-pass severity check, alongside clinical judgment.
How to calculate CURB-65
Each of the five criteria scores one point if present, for a total out of 5:
- Confusion — new disorientation in person, place, or time
- Urea — greater than 7 mmol/L (approximately 19 mg/dL BUN)
- Respiratory rate — 30 breaths per minute or higher
- Blood pressure — systolic below 90 mmHg, or diastolic 60 mmHg or below
- 65 — age 65 or older
A simplified version, CRB-65, drops the urea criterion (no blood test needed) and is sometimes used in primary care or resource-limited settings where labs aren't immediately available.
Interpretation
| Score | Risk | Typical management |
|---|---|---|
| 0–1 | Low | Outpatient treatment is often appropriate |
| 2 | Moderate | Consider hospital admission or closely supervised outpatient care |
| 3–5 | Severe | Consider hospitalization, possibly ICU-level care |
Limitations
CURB-65 is a decision-support tool, not a replacement for clinical judgment. It doesn't account for oxygen saturation, comorbidities (e.g. immunosuppression, significant cardiopulmonary disease), or social factors like the ability to manage safely at home — all of which can independently justify admission even with a low score. Always interpret the result alongside the full clinical picture and your institution's protocols.
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. National Institute for Health and Care Excellence (NICE) and British Thoracic Society (BTS) pneumonia management guidelines.
See also: Pneumonia Management — the full guide, including antibiotics by severity.