How should I determine the severity of CAP in a patient to guide management decisions?

To determine the severity of community-acquired pneumonia (CAP) in a patient and guide management decisions, use the CRB65 score in primary care and the CURB65 score in hospital settings.

CRB65 score (for use outside hospital): Assign 1 point for each of the following: confusion (new disorientation or abbreviated Mental Test score ≤8), respiratory rate ≥30 breaths/min, low blood pressure (diastolic ≤60 mmHg or systolic <90 mmHg), and age ≥65 years. Stratify risk of 30-day mortality as: 0 points = low risk (<1%), 1-2 points = intermediate risk (1-10%), 3-4 points = high risk (>10%). Use clinical judgement alongside the score, considering comorbidities, pregnancy, social circumstances, and oxygen saturation, to decide on hospital referral or home care. Consider hospital assessment for scores ≥2, shared decision-making for score 1, and home care for score 0 ¹,².

CURB65 score (for use in hospital): Assign 1 point for each of: confusion, blood urea nitrogen >7 mmol/L, respiratory rate ≥30 breaths/min, low blood pressure (diastolic ≤60 mmHg or systolic <90 mmHg), and age ≥65 years. Stratify mortality risk as: 0-1 points = low risk (<3%), 2 points = intermediate risk (3-15%), 3-5 points = high risk (>15%). Use this score with clinical judgement to guide management: consider home care for scores 0-1, hospital care for scores ≥2, and intensive care assessment for scores ≥3 ¹.

Additional considerations: Clinical judgement is essential as mortality scores may not fully capture severity, especially if oxygen saturation is low or other factors like frailty or pregnancy are present. Severity assessment informs decisions on microbiological testing, antibiotic choice, and level of care ¹,².