Scores & indices

CURB-65 calculator

Q: Can a CURB-65 of 0 still need admission?

Yes — the score omits oxygenation entirely, so a hypoxic patient needs admission regardless of a reassuring number. The in-app pneumonia work-up asks the oxygen question explicitly before sending anyone home.

Q: What do the scores mean numerically?

In the derivation cohort, 30-day mortality ran roughly 0.7% at 0, 2.1% at 1, 9.2% at 2, 14.5% at 3, and 40%+ at 4–5 — the basis for home (0–1), hospital (2), and severe (3+) management bands.

Q: Does it apply outside hospital settings without urea results?

Use CRB-65 in the community: the same criteria minus urea, with admission considered at 1 or more. The urea point adds prognostic power when bloods are available.

Five findings at the bedside, and the pneumonia disposition follows: home, ward, or thinking about ICU.

FreeNo sign-upWorks offlineNo patient data stored

Clinical judgement overrides the score — hypoxia and comorbidity matter.Reference: Lim et al., Thorax 2003.

How to read the result

CURB-65 falls into these published bands.

< 2Low severityConsider outpatient management.

2Moderate severityConsider hospital admission.

≥ 3SevereAdmit; assess for ICU, especially at 4–5.

Worked example

A confused patient with a urea of 9 mmol/L and a respiratory rate of 32.

CURB-65 3 — severe pneumonia (~14.5% 30-day mortality)

Admission territory with senior review; at 4–5 the assessment turns to ICU suitability.

Who this is for

For clinicians deciding where a patient with community-acquired pneumonia should be treated. Confusion, urea over 7 mmol/L, respiratory rate ≥ 30, low blood pressure, and age ≥ 65 each score one point; the total maps to 30-day mortality and the site-of-care decision per the derivation study and BTS guidance — with the caveat that hypoxia and clinical judgement override the number.

How it works

What it calculates

Severity of community-acquired pneumonia from five bedside variables, predicting 30-day mortality and guiding the site-of-care decision.

Interpreting the result

0–1: low severity, usually suitable for home treatment. 2: consider short admission or supervised outpatient care. 3–5: severe — admit, and assess for ICU at 4–5.

Limitations

It does not include oxygenation — a hypoxic patient with a low score still needs admission — and it under-triages young patients and the immunosuppressed (including HIV/TB co-infection, where scores understate risk). Clinical judgement overrides the number.

Built on published evidence

Lim et al., Thorax 2003

Codification last reviewed 2026-08-28, and checked against published reference values in automated tests on every release — see the full evidence ledger.

Questions clinicians ask

Can a CURB-65 of 0 still need admission?

Yes — the score omits oxygenation entirely, so a hypoxic patient needs admission regardless of a reassuring number. The in-app pneumonia work-up asks the oxygen question explicitly before sending anyone home.

What do the scores mean numerically?

In the derivation cohort, 30-day mortality ran roughly 0.7% at 0, 2.1% at 1, 9.2% at 2, 14.5% at 3, and 40%+ at 4–5 — the basis for home (0–1), hospital (2), and severe (3+) management bands.

Does it apply outside hospital settings without urea results?

Use CRB-65 in the community: the same criteria minus urea, with admission considered at 1 or more. The urea point adds prognostic power when bloods are available.

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