CURB-65 score of 3 – what does it mean?
⚠︎ Learning page – classification and study figures only, no treatment recommendation.
In short
A CURB-65 of 3 means that 3 of the 5 criteria are met. In the derivation cohort of Lim et al. (2003), 30-day mortality with 3 points was 17%. The validation cohort confirmed a similar pattern.
The figures describe groups in the cited studies, not the risk of an individual person. This page contains no treatment or management recommendation.
How a score of 3 comes about
Each of the five criteria scores 1 point: C – new-onset confusion, U – urea > 7 mmol/l, R – respiratory rate ≥ 30/min, B – systolic BP < 90 or diastolic ≤ 60 mmHg, 65 – age ≥ 65 years.
There are 10 combinations for 3 points:
- C (confusion) + U (urea) + R (respiratory rate)
- C (confusion) + U (urea) + B (blood pressure)
- C (confusion) + U (urea) + 65 (age)
- C (confusion) + R (respiratory rate) + B (blood pressure)
- C (confusion) + R (respiratory rate) + 65 (age)
- C (confusion) + B (blood pressure) + 65 (age)
- U (urea) + R (respiratory rate) + B (blood pressure)
- U (urea) + R (respiratory rate) + 65 (age)
- U (urea) + B (blood pressure) + 65 (age)
- R (respiratory rate) + B (blood pressure) + 65 (age)
What the original study describes
Lim et al. derived the score in 2003 from three prospective studies of community-acquired pneumonia from the UK, New Zealand and the Netherlands: 1,068 patients, mean age 64 years, overall 30-day mortality 9%. 80% of the data formed the derivation cohort, the rest was used for validation.
In the derivation cohort, 1 and 2 points were close together at 3.2% and 3%; from 3 points, 30-day mortality rose markedly (17%, 41.5%, 57%).
CURB-65 and CRB-65
The CRB-65 omits urea (0–4 points). With the same findings it therefore equals CURB-65, or is 1 point lower if urea is above 7 mmol/l. The mortality figures on this page apply to CURB-65 only.
All scores at a glance
Calculate it yourself
Enter the criteria in the CURB-65 score (pneumonia) calculator – it runs only in your browser.
FAQ
What does a CURB-65 of 3 mean?▾
3 of 5 criteria are met. In the derivation cohort of Lim et al. (2003), 30-day mortality at this score was 17%.
Which urea value counts?▾
The original study uses urea > 7 mmol/l, which is about 42 mg/dl urea or 19.6 mg/dl blood urea nitrogen (BUN).
Does the mortality apply to individual patients?▾
No. The percentages come from the 2003 study cohorts and describe groups, not an individual prognosis.
References
- Lim WS et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax 2003;58:377–82. · PubMed · full text (PMC)
Learning page for medical education only: classification and figures reported in the cited sources, no treatment or management recommendation, not for use in patients; not a medical device. Last updated: 10/2026 · Dr. Pascal Bafteh