For healthcare professionals
CURB-65 calculator (pneumonia severity)
CURB-65 is a 0 to 5 point score clinicians use when an adult presents to hospital with community acquired pneumonia. It gives one point each for confusion, raised urea, fast breathing, low blood pressure and age 65 or over, and higher scores went with higher 30-day mortality in the original study. This calculator is written for clinicians and is not a diagnosis.
Findings at first hospital assessment
Use the values from the initial assessment. Nothing you enter leaves this page.
What you will see
The CURB-65 score from 0 to 5, which items scored, and the 30-day mortality seen for that score in the original study.
Educational only, not medical advice. Not a diagnosis and not a decision on where to treat.
Source
Lim WS and colleagues, Thorax 2003, abstract: the five items, their cut points and the 30-day mortality for each score. The tests check every cut point and the mortality figure for each score. US context from the 2019 American Thoracic Society and Infectious Diseases Society of America pneumonia guideline.
Validated in
1,068 adults admitted to hospital with community acquired pneumonia in three prospective studies from the UK, New Zealand and the Netherlands (mean age 64, 30-day mortality 9%). The score was built in 80% of the data and tested in the rest (Lim 2003). It was developed in immunocompetent patients (ATS/IDSA 2019).
Limits
The mortality figures come from hospitalized patients in the early 2000s and may not match your setting. The score was not built for people with weakened immune systems, for hospital acquired pneumonia, or to choose ICU care. It leaves out oxygen levels, other illnesses and social factors, so clinical judgement still decides where a patient is treated. US guidance prefers the Pneumonia Severity Index over CURB-65 for that decision.
CURB-65 scoring
One point for each item present at the first hospital assessment, for a total of 0 to 5 (Lim 2003).
| Letter | Item | Point if |
|---|---|---|
| C | Confusion | Present |
| U | Urea | Above 7 mmol/L (BUN above about 19.6 mg/dL) |
| R | Respiratory rate | 30 per minute or more |
| B | Blood pressure | Systolic below 90 mm Hg, or diastolic 60 mm Hg or less |
| 65 | Age | 65 years or more |
The study reports urea in mmol/L. US labs report blood urea nitrogen (BUN) in mg/dL; one mmol of urea carries 28 mg of nitrogen, so this calculator divides BUN by 2.8 to get urea, and 7 mmol/L matches a BUN of about 19.6 mg/dL.
30-day mortality by score
In the derivation cohort, 30-day mortality rose with the score, and the validation cohort showed a similar pattern (Lim 2003).
| Score | 30-day mortality |
|---|---|
| 0 | 0.7% |
| 1 | 3.2% |
| 2 | 3% |
| 3 | 17% |
| 4 | 41.5% |
| 5 | 57% |
Source: abstract of Lim and colleagues, 2003 (Lim 2003). The authors proposed the score to sort adults with pneumonia into management groups at presentation (Lim 2003).
How US guidance uses it
The 2019 American Thoracic Society and Infectious Diseases Society of America guideline recommends using a validated prediction rule together with clinical judgement to decide whether an adult with pneumonia needs hospital care. It prefers the Pneumonia Severity Index (strong recommendation) over CURB-65 (conditional recommendation, low quality of evidence) (ATS/IDSA 2019). The guideline notes that the Pneumonia Severity Index classes more patients as low risk, that there is less evidence for CURB-65 as a decision aid on site of care, and that it kept a conditional recommendation for CURB-65 because it is simpler to use (ATS/IDSA 2019).
Neither score was designed to choose the level of care inside the hospital. For ICU decisions the guideline points to its own major and minor severity criteria, which include a respiratory rate of 30 or more, confusion and a BUN of 20 mg/dL or more (ATS/IDSA 2019).
Related tools
For a fuller measure of consciousness than the confusion item, see the Glasgow Coma Scale calculator. For other clinician scores on this site, see the Revised Cardiac Risk Index (RCRI) before surgery, the MELD score calculator and the Child-Pugh score calculator, the HEART score calculator for chest pain and the Wells score for DVT. For adults with suspected infection, see the qSOFA score calculator from the Sepsis-3 consensus. For a sore throat, see the Centor score calculator (McIsaac score) for the chance of strep throat. For kidney function from creatinine, see the eGFR calculator. To check whether a COPD breathing test is advised for people without symptoms, see the COPD screening check.
Sources
- Lim WS, van der Eerden MM, Laing R, Boersma WG, Karalus N, Town GI, Lewis SA, Macfarlane JT. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377-382. doi:10.1136/thorax.58.5.377. PMID 12728155. Abstract (score items, cut points and 30-day mortality by score). pmc.ncbi.nlm.nih.gov/articles/PMC1746657/
- Metlay JP, Waterer GW, Long AC, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67. doi:10.1164/rccm.201908-1581ST. PMID 31573350. Question 4 (prediction rules for site of care) and Table 1. pmc.ncbi.nlm.nih.gov/articles/PMC6812437/
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