CURB-65 Pneumonia Severity Score
Confusion, Urea, Respiratory rate, Blood pressure, Age ≥65
Assess severity of community-acquired pneumonia (CAP). CURB-65 score guides hospital admission and ICU referral decisions per BTS guidelines.
What is the CURB-65?
CURB-65 is the British Thoracic Society (BTS) validated severity scoring system for community-acquired pneumonia (CAP) in adults. It uses five variables to stratify patients into three risk groups, directly guiding site-of-care decisions: outpatient treatment, hospital admission, or HDU/ICU consideration. The five criteria — new confusion, raised urea, elevated respiratory rate, low blood pressure, and age ≥65 — each score one point, giving a maximum of 5. CURB-65 is simpler than the PSI/PORT score and is the preferred tool in UK clinical practice, endorsed by BTS and NICE.
When to use it
Apply to all adults with confirmed or suspected community-acquired pneumonia to guide site-of-care decisions. Not validated for hospital-acquired pneumonia or in patients with structural lung disease.
Scoring Criteria
CURB-65 — Variables & Points
Confusion (new disorientation in person, place, or time)
Urea > 7 mmol/L (BUN > 20 mg/dL)
Respiratory rate ≥ 30 breaths/min
Blood pressure: SBP < 90 or DBP ≤ 60 mmHg
Age ≥ 65 years
Score Interpretation
Low severity
Home treatment appropriate in most cases (30-day mortality <3%)
Moderate severity
Hospital-supervised treatment; consider short admission (mortality ~9%)
High severity
Urgent hospital admission; ICU/HDU assessment if score 4–5 (mortality 15–40%)
Guideline Recommendation
BTS CAP Guidelines (2009, updated 2022): CURB-65 is the recommended scoring tool for severity assessment in CAP. Score ≥3 requires hospital admission; score 4–5 warrants HDU/ICU consideration. Use alongside clinical judgement — social factors, comorbidities, and oxygen saturation also influence admission decisions.
Clinical Pearls
CRB-65 (without urea) is a valid alternative in primary care where urea is not immediately available.
CURB-65 is a severity tool, not a diagnostic tool — clinical presentation (oxygen saturation, respiratory examination, radiological confirmation) must guide the diagnosis.
Oxygen saturation <92% (or <94% in COPD patients) independently indicates hospital admission even with a low CURB-65 score.
In older patients, confusion may be the presenting sign of sepsis rather than classical pneumonia symptoms.
A score of 2 is a clinical judgment zone — consider social circumstances, comorbidities, and trajectory before deciding on outpatient vs inpatient management.
Limitations
Less discriminating than PSI/PORT for identifying very low-risk patients suitable for outpatient treatment.
Urea requires blood testing, which may delay scoring in resource-limited settings.
Not validated for healthcare-associated pneumonia or immunocompromised patients.
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Frequently Asked Questions
What CURB-65 score requires hospital admission?
A CURB-65 score of ≥2 indicates moderate-to-high severity and requires at least hospital-supervised treatment. Scores of ≥3 mandate hospital admission. Scores of 4–5 require consideration of ICU or high-dependency unit admission due to 30-day mortality rates of 15–40%.
What is the difference between CURB-65 and PSI score for pneumonia?
CURB-65 is simpler, uses five variables, and is the BTS/NICE preferred tool in the UK. The Pneumonia Severity Index (PSI/PORT) uses 20 variables and is more accurate at identifying very-low-risk patients suitable for outpatient treatment. PSI is preferred in North American practice (IDSA/ATS guidelines).