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CURB-65 Pneumonia Severity Score

Community-acquired pneumonia (CAP) severity tool. Used in Australian EDs and general practice to guide home vs hospital decisions.

📋 Sources: Lim WS et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax 2003;58:377–382 (score variables). NICE guideline NG250, Pneumonia: diagnosis and management (2025) (severity bands). BTS guidelines for the management of CAP in adults, Thorax 2009;64(Suppl III):1–55. thorax.bmj.com
UK guidance is cited. Australian Therapeutic Guidelines (eTG) were not accessed for this page. General information only, not medical advice. Your doctor knows your history and circumstances; follow their personalised advice over general information.
For clinicians & informed patients: CURB-65 is a decision aid, not a decision maker. Clinical judgement — including oxygen saturations, comorbidities, and social factors — always takes precedence.
C — Confusion
New disorientation in person, place or time (not pre-existing). AMTS ≤8 / 10, or new altered mental status.
U — Urea >7 mmol/L
Blood urea nitrogen >7 mmol/L (BUN >19.6 mg/dL). If urea is not available, a version without urea (CRB-65) exists.
R — Respiratory Rate ≥30/min
Count respirations for a full minute, at rest. ≥30 breaths/minute is abnormal in an adult.
B — Blood Pressure Low
Systolic <90 mmHg OR diastolic ≤60 mmHg.
65 — Age ≥65 years
Patient is 65 years old or older at time of assessment.
CURB-65 Score 0 / 5
Select variables above — result updates live.

CURB-65 is a validated clinical severity score for community-acquired pneumonia (CAP), developed by Lim et al. (Thorax 2003) and referenced in British Thoracic Society (BTS) and NICE pneumonia guidance.

Each letter represents one variable worth 1 point: Confusion (new), Urea >7 mmol/L, Respiratory rate ≥30/min, Blood pressure low (systolic <90 or diastolic ≤60 mmHg), and age ≥65. Total score ranges from 0–5.

In the original study (Lim et al. 2003), 30-day mortality rose as the score increased. Figures are not reproduced here; see the paper.

CURB-65 score Band (NICE NG250, 2025)
0–1Low risk (usually)
2Moderate risk
3 or moreHigh risk

Source: NICE NG250 (2025). Score variables: Lim WS et al. Thorax 2003;58:377–382. Where and how a person is treated is a decision for their treating clinician; this table is information only.

In CURB-65, confusion means new disorientation in person, place or time, not pre-existing dementia or chronic cognitive impairment. Some versions define it as an Abbreviated Mental Test Score (AMTS) of 8 or less out of 10.

Source: Lim WS et al. Thorax 2003;58:377–382.

CURB-65 is validated for community-acquired pneumonia (CAP) in adults. It is not validated for:

  • Hospital-acquired or ventilator-associated pneumonia
  • Aspiration pneumonia
  • Immunocompromised patients (HIV, solid organ transplant, chemotherapy)
  • Children

CURB-65 does not capture several important clinical factors. Always consider:

  • Oxygen saturation (SpO₂) — not in the score
  • Bilateral or multilobar involvement on CXR
  • Significant comorbidities (COPD, heart failure, diabetes, immunosuppression)
  • Social circumstances and ability to manage at home
  • Rapid deterioration or failure of outpatient treatment
  • Patient and family preferences

If urea is not available, a 4-variable version without urea (CRB-65) is used. NICE NG250 describes its primary-care bands as 0 low risk, 1–2 moderate risk, and 3–4 high risk.

This page does not give treatment or dosing information. Treatment choices are set out in current clinical guidelines such as Therapeutic Guidelines: Antibiotic (eTG, Australia; subscription) and NICE NG250. Dosing and drug choice depend on the individual and are for the treating clinician.

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