Curb 65 Score Calculator

CURB-65 was designed to answer one practical emergency-department question fast: does this patient with community-acquired pneumonia need to be admitted? Its five components — new confusion, blood urea nitrogen above 7 mmol/L (roughly 19-20 mg/dL), respiratory rate 30 or higher, systolic BP below 90 or diastolic below 60, and age 65 or older — are all rapidly available from a basic history, vital signs, and a single chemistry panel, deliberately excluding anything requiring a chest X-ray severity read or blood gas result so it can be scored within minutes of a patient hitting triage. Each criterion contributes equally (1 point each, 0-5 total), and the resulting tiers map directly onto a disposition decision: 0-1 supports outpatient treatment, 2 suggests a short inpatient stay or closely supervised outpatient management, and 3 or higher — carrying mortality that climbs sharply into the double digits — supports hospital admission with consideration of ICU-level care. A simplified CRB-65 variant that drops the urea criterion exists specifically for primary-care and outpatient settings where a same-visit lab result isn't available, trading a small amount of discrimination for immediate usability without blood work.

CURB-65 descends from the earlier British Thoracic Society 1987 pneumonia severity rule, which combined similar physiological criteria but had not been extensively externally validated across large multicenter cohorts. W.S. Lim and colleagues refined and validated the modern five-variable version in a 2003 Thorax paper using data pooled from over 1,000 patients across UK, New Zealand, and Netherlands hospitals, formally establishing the urea and confusion criteria alongside vital signs and age. CURB-65 was developed partly as a simpler, more bedside-practical alternative to the more complex, 20-variable Pneumonia Severity Index (PSI) published by Michael Fine and colleagues in the New England Journal of Medicine in 1997, which required more extensive laboratory and radiographic data to calculate. The British Thoracic Society formally incorporated CURB-65 into its national community-acquired pneumonia management guidelines in 2009, and the score has since been adopted internationally alongside PSI as one of the two standard tools referenced in IDSA/ATS pneumonia management guidelines.