Community-Acquired Pneumonia (CAP)

🔍 When to Suspect

An acute lower respiratory tract illness with cough, plus at least one other LRTI symptom (e.g., dyspnoea) and new focal chest signs on examination

From the full topic in The Ocean Library: Community-Acquired Pneumonia (CAP)

🧭 When to suspect

Community-acquired pneumonia (CAP) is an acute lower respiratory tract infection acquired outside hospital (or within 48 hours of admission), in which infection inflames the lung tissue itself. In primary care the diagnosis is clinical: suspect CAP in a patient with an acute cough plus at least one other lower respiratory tract symptom – breathlessness, pleuritic chest pain, sputum or wheeze – together with new focal chest signs on examination. Systemic features such as fever, sweats, rigors or malaise raise the probability further.

A chest X-ray is not needed to make the diagnosis in the community. Once CAP is diagnosed clinically, two decisions dominate: stratify severity using the CRB65 score alongside clinical judgement, and decide the safest place of care. Most patients are managed at home, but the 2025 NICE update widened the middle ground – a virtual ward, same-day emergency care (SDEC) or hospital-at-home service now sit between “home” and “admit”.

The CRB65 score gives 1 point each for Confusion (new disorientation, or abbreviated Mental Test score ≤ 8), Respiratory rate ≥ 30/min, low Blood pressure (systolic < 90 mmHg or diastolic ≤ 60 mmHg) and age ≥ 65. It estimates 30-day mortality risk and guides – but never replaces – the place-of-care decision. (In hospital, the CURB65 score adds a point for Urea > 7 mmol/L.)

CRB65 score	30-day mortality risk	Severity	Suggested place of care
0	< 1% (low)	Low	Primary care-led, with safety-netting
1	1–10% (intermediate)	Low–moderate	Primary care-led with safety-netting, or refer to virtual ward / SDEC / hospital-at-home / hospital
2	1–10% (intermediate)	Moderate	Consider referral to hospital (or virtual ward / SDEC / hospital-at-home)
3–4	> 10% (high)	High	Refer to hospital; consider critical care

Refer regardless of the score if there are features of sepsis or cardiorespiratory failure, or if the patient cannot take oral medicines.

Source: NICE NG250

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