Calculators · Respiratory Medicine · Score

CURB-65 and CRB-65

Also called CURB65, CRB65, pneumonia severity score BTS

30-day mortality and site of care in community-acquired pneumonia; CRB-65 when urea is not available.

Urea

7 mmol/L urea ≈ 42 mg/dL blood urea ≈ 19.6 mg/dL BUN.

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Formula and scoring

One point each: Confusion, Urea >7 mmol/L, RR ≥30, SBP <90 or DBP ≤60, age ≥65. CURB-65 0–1 low, 2 intermediate, 3–5 severe. CRB-65 0 low, 1–2 intermediate, 3–4 high.

Exam and ward pearls

  • Indian labs report blood urea in mg/dL: >42 mg/dL urea (or BUN >19.6 mg/dL) equals >7 mmol/L.
  • ATS/IDSA 2019 prefers PSI over CURB-65 for the admission decision.

When not to rely on it

  • Does not capture hypoxaemia, comorbidity or social circumstances; clinical judgement overrides a low score.

Source

  1. Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377-82. doi:10.1136/thorax.58.5.377 · PMID 12728155
  2. Alyami SM, et al. The Saudi Thoracic Society evidence-based guidelines for the diagnosis and management of community-acquired pneumonia in children and adults. Ann Thorac Med. 2025;20(4):195-212. (Tables 2-5: CURB-65 management sites and PSI points.) doi:10.4103/atm.atm_293_25 · PMID 41234760
  3. Ma CM, Wang N, Su QW, Yan Y, Yin FZ. The performance of CURB-65 and PSI for predicting in-hospital mortality of community-acquired pneumonia in patients with type 2 diabetes. Diabetes Metab Syndr Obes. 2021;14:1359-1366. (States the CRB-65 risk groups.) doi:10.2147/DMSO.S303124 · PMID 33790603

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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