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Lim WS, et al. "Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study". Thorax. 2003. 58(5):377-382.
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Clinical Question

In adults admitted with community-acquired pneumonia, what risk factors are associated with mortality and determine whether patients should be treated as an outpatient or inpatient?

Bottom Line

The CURB-65 score is an easy-to-use scoring system to assess community-acquired pneumonia (CAP) severity and triage patients accordingly.

Major Points

Assessing the risk of CAP and determining whether patients should be treated as out- or inpatients was elusive until several studies demonstrated a method of classifying patients into severe disease. Yet prior to CURB-65, no study had studied the classification of patients into low-risk cohorts; ie, those with mild disease that were suitable for outpatient management. Using a derivation cohort and validating it against a smaller cohort, CURB-65 identified a 6-point system based on the presence of confusion, urea >7 mmol/L (>20 mg/dl), respiratory rate ≥30/min, low blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg), and age ≥65 years. Scores of 0 to 1 were associated with low (<2%) 30-day mortality, a score of 2 was associated with intermediate (9.2%) mortality, and scores of ≥3 were associated with high (22%) mortality.


  • Review of three prospective studies from multiple centers
  • N=1068 (80% for derivation, 20% for validation)


Inclusion Criteria

  • Adults admitted through ED
  • CAP, defined as
    • Acute respiratory tract illness
    • New shadowing on admission CXR consistent with infection

Exclusion Criteria

  • CAP not the primary reason for admission
  • CAP an expected terminal event
  • Postobstructive pneumonia
  • Tuberculosis
  • Bronchiectasis
  • Malignancy
  • HIV
  • Hospitalization within prior 14 days
  • Immunocompromised status
  • Nursing home residents


  • Patients seen by study investigator within 24 hours of admission
  • Multivariate analysis of derivation cohort, validation against separate cohort


Primary Outcomes

30-day mortality
1.5% for score of 0 or 1
9.2% for score of 2
22% for score ≥3


Funding provided by Nottingham local trust fund, educational grant from Hoechst Marion Roussel, Health Research Council of New Zealand, and grants from Astra Zeneca BV Netherlands and Pfizer BV Netherlands.