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CURB-65

Severity and site of care in community-acquired pneumonia

Sources last checked: 2026-10-13

CURB-65

Severity and site of care in community-acquired pneumonia

0
0–1 — low severity

30-day mortality < 3 % (NICE NG250). NICE NG250 describes home-based care, with safety-netting, as usually appropriate in this group.

Validated for community-acquired pneumonia in adults, not hospital-acquired or aspiration pneumonia. Hypoxaemia, comorbidity and social circumstances are not in the score — use clinical judgement alongside it.

Source: 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.Open

Interpretation

0–1 — low severity30-day mortality < 3 % (NICE NG250). NICE NG250 describes home-based care, with safety-netting, as usually appropriate in this group.
2 — moderateMortality 3–15 % (NICE NG250). NICE NG250 names short-stay inpatient or hospital-supervised outpatient care as options in this group.
3–5 — high severityMortality > 15 % (NICE NG250). NICE NG250 classes this as high-severity pneumonia managed in hospital; BTS names assessment for critical care, especially at 4–5.

What is the CURB-65?

CURB-65 estimates 30-day mortality in adults with community-acquired pneumonia from five items: Confusion, Urea > 7 mmol/L, Respiratory rate ≥ 30/min, low Blood pressure, and age ≥ 65. Lim and colleagues derived it in 2003 from 1,068 patients in the UK, New Zealand and the Netherlands; mortality rose from 0.7 % at score 0 to 57 % at score 5. NICE NG250 (2025) and the BTS guideline use it to guide place of care in hospital.

When to use it

  • Adults with a clinical and radiological diagnosis of community-acquired pneumonia assessed in hospital.
  • To support the decision between home treatment, short-stay or ambulatory care, and inpatient admission.
  • To flag the high-severity group (3–5 points), in which BTS names assessment for critical care, especially at 4–5.

When not to use it

  • Primary care without blood tests — use CRB-65 (no urea).
  • Hospital-acquired, ventilator-associated or aspiration pneumonia, and severely immunocompromised patients.
  • As the only criterion for ICU admission — hypoxaemia, septic shock and the ATS/IDSA major criteria are not in the score.

How it is calculated

CriterionPoints
Confusion (AMTS ≤ 8 or new disorientation in person, place or time)+1
Urea > 7 mmol/L (≈ BUN > 19.6 mg/dL)+1
Respiratory rate ≥ 30/min+1
Systolic BP < 90 mmHg or diastolic ≤ 60 mmHg+1
Age ≥ 65+1

Clinical pearls and limitations

  • Validated for community-acquired pneumonia in adults, not hospital-acquired or aspiration pneumonia. Hypoxaemia, comorbidity and social circumstances are not in the score — use clinical judgement alongside it.
  • Urea 7 mmol/L corresponds to about 42 mg/dL urea or 19.6 mg/dL blood urea nitrogen (BUN) — check which your laboratory reports.
  • Confusion means an abbreviated mental test score ≤ 8 or new disorientation in person, place or time.
  • The score underestimates severity in young patients with hypoxaemia and overestimates it in older patients with few other problems — always pair it with clinical judgement.
  • The German S3 guideline uses CRB-65 together with oxygenation and functional status instead of CURB-65.

Frequently asked questions

CURB-65 vs CRB-65 — what is the difference?

CRB-65 omits urea, so it can be used in primary care without blood tests. NICE uses CRB-65 in primary care (0: < 1 % mortality; 1–2: 1–10 %; 3–4: > 10 %) and CURB-65 in hospital.

What CURB-65 score requires hospital admission?

NICE NG250 suggests considering inpatient care at 3 or more, ambulatory options (virtual ward, same-day emergency care) or admission at 2, and home treatment with safety-netting at 0–1. Social circumstances, hypoxaemia and comorbidity can override the score.

What mortality does each CURB-65 score predict?

In the 2003 derivation study: 0 points 0.7 %, 1 point 3.2 %, 2 points 13 %, 3 points 17 %, 4 points 41.5 %, 5 points 57 %. NICE groups these into < 3 %, 3–15 % and > 15 %.

Evidence and guidelines

  1. Primary source: 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.
  2. NICE guideline NG250. Pneumonia: diagnosis and management (2025) — CURB65 in hospital, CRB65 in primary care; risk bands and place of care.
  3. Lim WS et al. BTS guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax 2009;64(Suppl 3):iii1-iii55.

Have a follow-up question?

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