What is the CURB-65 score?

CURB-65 is a validated severity scoring system for community-acquired pneumonia. It assigns one point each for: Confusion, Urea >7 mmol/L, Respiratory rate ≥30/min, low Blood pressure (SBP <90 or DBP ≤60 mmHg), and age ≥65. Scores range 0–5 and predict 30-day mortality, guiding admission decisions.

At what CURB-65 score should a patient be admitted to hospital?

BTS guidelines recommend: Score 0–1 = low severity, consider outpatient treatment. Score 2 = moderate severity, consider hospital admission. Score 3–5 = high severity, hospital admission required, score ≥4 consider ICU assessment.

CURB-65 Score Calculator – Pneumonia Severity

Q: At what CURB-65 score should a patient be admitted to hospital?

BTS guidelines recommend: Score 0–1 = low severity, consider outpatient treatment. Score 2 = moderate severity, consider hospital admission. Score 3–5 = high severity, hospital admission required, score ≥4 consider ICU assessment.

About the CURB-65 Score

CURB-65 was developed by Lim et al. (2003) from the British Thoracic Society (BTS) CAP guidelines and validated in over 1,000 patients across three countries. It is the most widely used pneumonia severity scoring tool in the UK and is recommended alongside PSI (Pneumonia Severity Index) in the IDSA/ATS 2007 guidelines.

30-Day Mortality by Score

Score	30-Day Mortality	BTS Recommendation
0	~0.7%	Outpatient treatment
1	~2.1%	Outpatient or short admission
2	~9.2%	Hospital admission
3	~14.5%	Hospital admission; consider ICU
4	~40.0%	Urgent hospital; ICU assessment
5	~57.0%	ICU-level care

CRB-65 — Community Version Without Bloods

The CRB-65 score omits the urea criterion (U), making it usable in primary care and community settings where blood tests may not be immediately available. It uses the same C, R, B, and 65 criteria (max score 4). Score 0 = low risk (outpatient); score 1–2 = intermediate; score 3–4 = high risk (urgent admission).

CURB-65 vs PSI

The Pneumonia Severity Index (PSI) uses 20 variables and is more accurate for identifying low-risk patients safe for outpatient treatment. CURB-65 is simpler and faster to calculate — making it more practical at the bedside. Both tools are recommended by IDSA/ATS. CURB-65 is preferred in UK and European practice; PSI is more commonly used in North America.

Frequently Asked Questions

Can a patient with CURB-65 of 0 be safely treated at home?+

Generally yes — a CURB-65 of 0 is associated with a 30-day mortality of approximately 0.7%, and outpatient treatment is appropriate for most patients. However, CURB-65 should not be used in isolation. Consider social circumstances (ability to take oral medications, adequate home support), presence of significant comorbidities not captured by CURB-65, oxygen saturation, and ability to follow up. A score of 0 is a starting point — clinical judgement remains essential.

What other criteria should trigger ICU referral beyond CURB-65?+

IDSA/ATS minor criteria for ICU admission include: RR ≥30/min, PaO₂/FiO₂ <250, multilobar infiltrates, confusion/disorientation, BUN ≥20 mg/dL, leukopenia (WBC <4,000), thrombocytopenia (platelets <100,000), hypothermia (<36°C), and hypotension requiring aggressive fluid resuscitation. Major criteria are: septic shock requiring vasopressors or mechanical ventilation. Presence of 3 or more minor criteria also indicates ICU-level care.

Related Tools on MediCalc Pro

For neurological status in severe pneumonia, see Glasgow Coma Scale. For ICU mortality prediction, see APACHE II Score. For renal function and antibiotic dosing, see Creatinine Clearance. For DVT/PE risk in immobile pneumonia patients, see Wells Score. For converting urea units (mmol/L to mg/dL), see Lab Values Converter. For IV antibiotic infusion rates, see IV Drip Rate Calculator.

References

Lim WS, et al. "Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study." Thorax. 2003;58(5):377-382.
Mandell LA, et al. "Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults." Clin Infect Dis. 2007;44(Suppl 2):S27-72.
NICE Guideline NG138. Pneumonia (community-acquired): antimicrobial prescribing. NICE, 2019.

⚠️ Medical Disclaimer: CURB-65 is a severity tool to support — not replace — clinical judgement. All admission and management decisions must incorporate the full clinical picture including oxygenation, comorbidities, and social circumstances.