CURB-65 pneumonia severity score (criteria and application)
CURB-65 is a 5-item clinical prediction rule for adults with community-acquired pneumonia (CAP) used to estimate short-term mortality risk and support site-of-care decisions. The score uses Confusion, Urea/BUN level, Respiratory rate, Blood pressure, and Age ≥65 years. (eguideline.guidelinecentral.com)
CURB-65 components
Each item is scored as 1 point (total score 0–5). (eguideline.guidelinecentral.com)
- Confusion (1 point)
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Documented confusion assessed clinically (often operationalized as abnormal mental status such as disorientation). (eguideline.guidelinecentral.com)
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Urea/BUN (1 point)
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BUN >20 mg/dL (equivalent to urea above the usual CAP score threshold in common implementations). (eguideline.guidelinecentral.com)
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Respiratory rate (1 point)
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RR ≥30 breaths/min. (eguideline.guidelinecentral.com)
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Blood pressure (1 point)
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Systolic BP <90 mmHg or Diastolic BP ≤60 mmHg. (eguideline.guidelinecentral.com)
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Age (1 point)
- Age ≥65 years. (eguideline.guidelinecentral.com)
How to apply CURB-65 at the bedside
CURB-65 should be calculated at initial evaluation for adults with suspected/confirmed CAP. (eguideline.guidelinecentral.com)
Steps for calculation:
- Assign 1 point for each met criterion using vitals and basic labs available at presentation. (eguideline.guidelinecentral.com)
- Compute the total score (0–5). (eguideline.guidelinecentral.com)
- Use the score with clinical judgment to determine the most appropriate site of care. [1]
Monotherapy vs combination therapy (site-of-care vs antibiotic selection)
CURB-65 is a site-of-care/severity tool and does not determine antibiotic choice by itself. [2]
Antibiotic selection should be based on CAP guideline recommendations (setting of care, severity, comorbidities, local resistance risk, and allergy history), while CURB-65 supports severity-risk stratification. [2]
Treatment initiation thresholds (site-of-care recommendations using CURB-65)
Common CURB-65 thresholding for CAP site-of-care is: (eguideline.guidelinecentral.com)
- Score 0
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Low risk; consider home treatment. (eguideline.guidelinecentral.com)
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Score 1
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Low risk; consider home treatment. (eguideline.guidelinecentral.com)
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Score 2
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Admit to ward (or inpatient evaluation depending on local practice and clinical context). (eguideline.guidelinecentral.com)
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Score 3
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Severe pneumonia; hospitalize and consider ICU. (eguideline.guidelinecentral.com)
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Score 4–5
- Severe pneumonia; hospitalize and consider ICU. (eguideline.guidelinecentral.com)
Key evidence supporting CURB-65 thresholds
Mortality risk increases with CURB-65 score in CAP cohorts. [3]
Quantified examples reported in guideline discussion:
- CURB-65 = 0 mortality reported as ~1.2% in a cohort summary. [3]
- CURB-65 = 3–4 associated with ~31% mortality in the same guideline discussion. [3]
Important clarifications and nuances
- CURB-65 is not equivalent to ICU criteria. Direct ICU admission is recommended for patients with septic shock requiring vasopressors or respiratory failure requiring mechanical ventilation, regardless of the CURB-65 score. [2]
- CURB-65 should be used with clinical judgment due to differences in patient context and limitations of any single prediction rule. [1]
- Some guidelines prioritize the Pneumonia Severity Index (PSI/PORT) over CURB-65 for determining hospitalization need, but CURB-65 remains widely used for rapid risk stratification. [2]
Common pitfalls to avoid
- Relying on CURB-65 alone for ICU decisions leads to misclassification when major ICU triggers are present. [2]
- Incorrect unit handling for Urea/BUN can change scoring. The commonly operationalized laboratory threshold in CAP decision tools is BUN >20 mg/dL. (eguideline.guidelinecentral.com)
- Under-scoring confusion can occur when delirium is present but not documented as “confusion” in the score component. [1]
Target outcomes of using CURB-65
CURB-65 is intended to reduce harm from inappropriate site-of-care by identifying low-risk patients suitable for outpatient management and higher-risk patients needing admission and higher-level monitoring. [4]