CURB-65 Calculator
Community-Acquired Pneumonia Severity & Admission Guide
Select All That Apply (1 point each)
New disorientation in person, place, or time (AMT ≤8)
Blood urea nitrogen (BUN) > 19 mg/dL
Tachypnoea is a marker of respiratory compromise
Systolic < 90 mmHg or Diastolic ≤ 60 mmHg
Advanced age independently increases mortality risk
CURB-65 Score Interpretation Table
| Score | Group | 30-Day Mortality | Recommended Action |
|---|---|---|---|
| 0 | Group 1 | 0.7% | Home treatment likely appropriate |
| 1 | Group 1 | 2.1% | Home treatment; reassess if no improvement in 48h |
| 2 | Group 2 | 6.6% | Consider hospitalization or supervised outpatient care |
| 3 | Group 3 | 17.0% | Urgent inpatient admission; treat as severe CAP |
| 4–5 | Group 3 | ≈40% | Emergency admission; consider ICU assessment |
What is the CURB-65 Score?
The CURB-65 score is a validated clinical prediction rule developed by Lim et al. in 2003 and endorsed by the British Thoracic Society (BTS) for stratifying the severity of community-acquired pneumonia (CAP). It uses five easily obtainable bedside and laboratory parameters to estimate 30-day all-cause mortality and guide the decision between outpatient, inpatient, and intensive care management.
Each parameter present is assigned 1 point. A total score ranges from 0 to 5. The score was derived from a cohort of over 1,000 patients across multiple UK hospitals and has since been externally validated in numerous international populations, including studies from India and Southeast Asia.
When to Use CURB-65
CURB-65 is best applied in emergency departments and inpatient wards where blood urea/BUN results are readily available. For primary care or community settings without lab access, the abbreviated CRB-65 (dropping the Urea parameter) is recommended as a practical alternative. Always interpret the score alongside clinical judgment, oxygenation status, radiology findings, and social circumstances.
Antibiotic Guidance by Severity
The IDSA/ATS guidelines recommend oral amoxicillin-clavulanate or respiratory fluoroquinolones for mild CAP (score 0–1), and IV beta-lactam plus a macrolide for moderate-severe CAP (score ≥2). For ICU-level patients, dual coverage with a beta-lactam plus either a macrolide or fluoroquinolone is standard. Atypical coverage (Legionella, Mycoplasma) should be considered in all hospitalized CAP patients.
Limitations to Be Aware Of
- Does not incorporate oxygenation or SpO₂ directly — a patient with SpO₂ <90% may score low but require admission
- Urea may be elevated due to dehydration, renal disease, or upper GI bleeding — false positivity is possible
- Does not assess bilateral or multilobar infiltrates, which independently worsen prognosis
- Not validated in aspiration pneumonia, healthcare-associated pneumonia, or immunocompromised hosts
- Functional status, social support, and comorbidities must supplement the numeric score
Frequently Asked Questions
What does CURB-65 stand for?
CURB-65 is an acronym: C = Confusion, U = Urea >7 mmol/L, R = Respiratory Rate ≥30/min, B = low Blood Pressure, and 65 = Age ≥65 years. Each criterion present adds 1 point to the total score.
What is the difference between CURB-65 and CRB-65?
CRB-65 omits the blood urea parameter, making it usable when laboratory results aren't available — primarily in GP or primary care settings. CURB-65 has superior predictive accuracy and is preferred in hospitals where a blood urea or BUN result can be obtained quickly.
What CURB-65 score needs ICU admission?
A score of 4 or 5 carries a 30-day mortality approaching 40% and should trigger an urgent ICU assessment in addition to inpatient admission. A score of 3 also warrants hospital admission and management as severe pneumonia, with a lower threshold for ICU referral if the patient deteriorates.
Can CURB-65 be used for COVID-19 pneumonia?
CURB-65 was not validated for viral or COVID-19 pneumonia. It can provide a rough severity estimate, but dedicated scores such as the 4C Mortality Score or WHO severity classification are more appropriate for SARS-CoV-2 pneumonia assessment.