What are the key clinical features to consider when diagnosing community-acquired pneumonia (CAP) in adults?

Key clinical features to consider when diagnosing community-acquired pneumonia (CAP) in adults include:

• Symptoms of lower respiratory tract infection such as cough (usually productive), breathlessness, chest discomfort or pain, and sputum production without an alternative explanation like asthma or sinusitis.
• Systemic features such as fever (temperature often >37.5°C), malaise, and abnormal mental status including confusion or new disorientation.
• Vital sign abnormalities including raised respiratory rate (≥30 breaths per minute), tachycardia (heart rate >100 beats per minute), and hypotension (systolic blood pressure <90 mmHg or diastolic ≤60 mmHg).
• Oxygen saturation under 90% on room air indicating hypoxia.
• Physical examination findings of focal chest signs suggestive of pneumonia, such as localized crackles or bronchial breath sounds.
• Risk factors such as age ≥65 years, comorbidities, and inability to eat without assistance may also support the diagnosis and influence severity assessment.

Diagnosis is primarily clinical, supported by these features, and may be confirmed by chest X-ray if available, especially in hospital settings. The CRB65 score, which includes confusion, respiratory rate, blood pressure, and age ≥65, is used to assess severity and guide management decisions.

Overall, the diagnosis relies on a combination of lower respiratory symptoms, systemic signs, vital sign abnormalities, and clinical judgment in the absence of alternative diagnoses.

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