CURB-65 (Lim 2003) grades community-acquired pneumonia (CAP) severity from 5 criteria. Each criterion present = 1 point (total 0–5).
- C — Confusion: new disorientation in person, place, or time, or an Abbreviated Mental Test (AMT) score ≤8
- U — Urea >7 mmol/L (BUN >19–20 mg/dL)
- R — Respiratory rate ≥30 breaths/min
- B — Blood pressure: systolic <90 mm Hg or diastolic ≤60 mm Hg
- 65 — Age ≥65 years
Score interpretation (30-day mortality, disposition):
- 0–1: Low risk (~1.5%) — consider outpatient treatment
- 2: Moderate risk (~9.2%) — short inpatient admission or supervised outpatient / hospital-at-home
- 3–5: High/severe risk (~22% at 3, up to ~57% at 5) — hospitalize; at 4–5 assess for ICU/critical care
All computation runs in your browser; no values are stored or transmitted.
When to Use
Appropriate population
- Adults with a clinical and radiographic diagnosis of community-acquired pneumonia, scored at presentation
- Triage decision support: outpatient vs. ward admission vs. critical-care assessment
- CKD/dialysis patients — functionally immunocompromised with high acute-kidney-injury risk from sepsis-driven hemodynamic compromise; CURB-65 helps flag those needing inpatient care early
- Primary-care or pre-hospital settings without labs can use the CRB-65 variant (omits Urea)
Pearls & Pitfalls
Key pearls
- CURB-65 supports — never replaces — clinical judgment; young patients with hypoxemia or unstable comorbidity may need admission despite a low score
- CKD caveat: baseline urea is often elevated in CKD and dialysis patients, which can inflate the U criterion. Interpret the urea point against the patient's baseline, not a single threshold
- CKD/dialysis patients are functionally immunocompromised and prone to sepsis-driven AKI and hemodynamic collapse — escalate care promptly even at moderate scores
- Confusion is the strongest single predictor of mortality; document the mental-status baseline
- The Blood-pressure criterion is met by either systolic <90 mm Hg or diastolic ≤60 mm Hg (only 1 point regardless)
- CRB-65 (no Urea) is a useful lab-free bedside variant in primary care; PSI/PORT is the more granular alternative when richer data are available
Why Use It · CRB-65 & PSI/PORT
CURB-65 is a fast, validated bedside rule that turns five readily available variables into a 30-day mortality estimate and a clear disposition recommendation, helping clinicians avoid both unsafe discharges and unnecessary admissions.
CRB-65 — the lab-free variant
CRB-65 omits the Urea criterion, scoring only Confusion, Respiratory rate, Blood pressure, and Age ≥65. It was designed for primary-care and pre-hospital settings where blood tests are not immediately available, trading a small amount of discrimination for bedside speed.
PSI / PORT — the detailed alternative
The Pneumonia Severity Index (PSI/PORT, Fine 1997) is a more detailed 20-variable rule incorporating demographics, comorbidities, examination findings, and laboratory and radiographic data to assign patients to risk classes I–V (class I lowest, class V highest 30-day mortality). PSI is more granular and is often favored for identifying truly low-risk patients suitable for outpatient care, but it is more cumbersome to compute. CURB-65 is the simpler bedside tool and is the interactive calculator provided here; the full 20-variable PSI is not built on this page.
CURB-65 Calculator
Check each criterion that is present. The score, 30-day mortality estimate, and recommended setting update automatically.
Check all that apply (each = 1 point)
⚕ CURB-65 supports but does not replace clinical judgment. Mortality estimates are derived from validation cohorts and may not apply to an individual patient. In CKD/dialysis, baseline-elevated urea can inflate the U criterion — interpret accordingly. For educational reference only. Reference: Lim WS et al., Thorax 2003.
Next Steps
- Score 0–1: Consider outpatient treatment with oral antibiotics if no other contraindication; arrange follow-up and safety-net advice
- Score 2: Consider short inpatient admission or supervised outpatient / hospital-at-home care
- Score 3–5: Hospitalize; manage as severe pneumonia. At 4–5, assess promptly for ICU/critical-care admission
- CKD/dialysis: Adjust antibiotic dosing for renal function, monitor closely for sepsis-driven AKI and hemodynamic instability, and lower the threshold to escalate care
- Pair severity scoring with guideline-based antibiotic selection (ATS/IDSA 2019) and reassessment within 48–72 h
Evidence & References
References
- Lim WS, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study (CURB-65). Thorax. 2003;58(5):377–382.
- Fine MJ, et al. A prediction rule to identify low-risk patients with community-acquired pneumonia (PSI/PORT). N Engl J Med. 1997;336(4):243–250.
- Metlay JP, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia (ATS/IDSA). Am J Respir Crit Care Med. 2019;200(7):e45–e67.
