CURB-65 Calculator

How to Use This Calculator

1. Select Yes/No for each of the 5 CURB-65 criteria.
2. Score (0–5), 30-day mortality, and disposition recommendation display instantly.
3. CRB-65 tab omits BUN for primary care use.
4. Mortality Table tab includes IDSA/ATS antibiotic guidance by severity.

Formula

Example

Frequently Asked Questions

• What is CURB-65 used for? ▼
  CURB-65 is a validated clinical prediction rule developed by Lim and colleagues and published in Thorax in 2003 to assess the severity of community-acquired pneumonia (CAP) and guide triage and disposition decisions. The score incorporates five readily available clinical and laboratory variables: Confusion (new disorientation to person, place, or time); elevated Blood Urea Nitrogen (BUN >19 mg/dL or urea >7 mmol/L in UK units); Respiratory Rate ≥30 breaths per minute; abnormal Blood Pressure (systolic <90 mmHg or diastolic ≤60 mmHg); and Age ≥65 years. Each criterion scores one point, producing a total of 0–5. The score stratifies patients into three risk classes: low risk (score 0–1) with 30-day mortality of approximately 0.7–2.1%, suitable for outpatient treatment; moderate risk (score 2) with 9.2% mortality, suggesting short inpatient admission or close outpatient supervision; and high risk (score 3–5) with 14.5–57% mortality, indicating hospital admission with ICU consideration for scores ≥4. CURB-65 is endorsed by the British Thoracic Society (BTS) guidelines as a primary severity assessment tool for all adults presenting with suspected CAP.
• When should I admit a pneumonia patient based on CURB-65? ▼
  CURB-65 provides evidence-based disposition guidance, but clinical judgement must supplement it, particularly for borderline scores. Score 0–1: outpatient antibiotic treatment is safe and appropriate for otherwise healthy patients with good social support, ability to tolerate oral medications, and no concerning clinical features such as oxygen desaturation, bilateral infiltrates, or rapid progression. Patients should be given clear return precautions and follow-up within 24–48 hours. Score 2: a short inpatient admission or supervised outpatient treatment with same-day clinic review is recommended. Many centres admit score-2 patients, particularly the elderly or those with comorbidities. Score 3: hospital admission is indicated; monitoring for clinical deterioration is essential. Score 4–5: hospital admission mandatory; high-dependency or ICU-level care should be considered. The ATS/IDSA "severe CAP" criteria include two independent pathways — either one major criterion (septic shock requiring vasopressors or mechanical ventilation) or three or more minor criteria (RR ≥30, PaO2/FiO2 <250, multilobar infiltrates, confusion, BUN ≥20 mg/dL, WBC <4000/mm³, platelet <100,000/mm³, temperature <36°C, hypotension requiring aggressive IV fluids). Social circumstances, ability to comply with oral therapy, oxygenation status, and the presence of comorbidities that may complicate outpatient management are additional factors guiding admission.
• Should I use CURB-65 or PSI/PORT score? ▼
  Both CURB-65 and the Pneumonia Severity Index (PSI/PORT score) are validated for predicting 30-day mortality in CAP, but they have different practical profiles. CURB-65 has five variables and takes under a minute to calculate, making it highly practical for emergency department triage and primary care settings. It slightly over-estimates severity in younger patients because age ≥65 alone contributes a point regardless of other parameters. PSI uses 20 variables including extensive demographics, comorbidities, examination findings, laboratory results, and chest imaging — requiring 5–10 minutes to calculate. PSI is better at identifying truly low-risk patients for safe outpatient treatment and is particularly useful in academic hospital settings with full laboratory access. Multiple validation studies, including the meta-analysis by Loke et al., showed PSI has superior discrimination (C-statistic 0.82 vs 0.76 for 30-day mortality) but both perform adequately. IDSA/ATS 2019 guidelines endorse both tools; BTS guidelines prefer CURB-65. In practice, many physicians use CURB-65 for initial bedside triage and apply PSI to refine management in borderline cases. Neither score should override clinical judgement: a CURB-65 score of 1 with hypoxia, rapidly spreading infiltrates, or inability to maintain oral intake warrants admission regardless of score.
• What is the difference between CURB-65 and CRB-65? ▼
  CRB-65 is a simplified variant of CURB-65 that omits the Blood Urea Nitrogen (BUN) criterion, using only four variables: Confusion, Respiratory Rate ≥30/min, low Blood Pressure (SBP <90 or DBP ≤60 mmHg), and Age ≥65. It was developed specifically for community (primary care) settings where laboratory results may not be immediately available. The CRB-65 score ranges from 0–4. Risk stratification: score 0 = low risk (~1% mortality) — community treatment; score 1–2 = intermediate risk — consider hospital; score 3–4 = high risk — urgent hospital admission. CRB-65 has been validated in multiple primary care cohorts and performs comparably to CURB-65 for identifying high-risk patients, though its discrimination for low-risk patients is slightly inferior to the full CURB-65 due to the loss of the BUN criterion. In practice, CRB-65 is ideal when a general practitioner or urgent care physician is assessing a patient at home or in a clinic without point-of-care blood testing. Once the patient reaches an emergency department or hospital, the full CURB-65 (with BUN) should be calculated. Some geriatric guidelines also recommend adding an oxygenation criterion (SpO2 < 92% or PaO2 < 60 mmHg) to either CURB-65 or CRB-65, as hypoxaemia significantly modifies management in elderly patients.
• Are there pneumonia scores better than CURB-65 for ICU triage? ▼
  CURB-65 was developed and validated primarily for predicting 30-day mortality and guiding ward-level disposition decisions, not specifically for identifying patients who require ICU care. For ICU triage, the ATS/IDSA Severe CAP criteria are more appropriate: "severe CAP" is defined by the presence of any major criterion (need for mechanical ventilation or septic shock requiring vasopressors) or ≥3 minor criteria from a list of 9 (RR ≥30, PaO2/FiO2 <250, multilobar infiltrates, confusion/disorientation, BUN ≥20 mg/dL, white cell count <4,000/mm³, platelet count <100,000/mm³, core temperature <36°C, hypotension requiring aggressive IV resuscitation). The SCAP score (Severe Community-Acquired Pneumonia) and the SMART-COP score were specifically developed to predict need for intensive respiratory or vasopressor support (IRVS) and have higher sensitivity for ICU-level care than CURB-65. SMART-COP assigns 2 points for low blood pressure (SBP <90) and low albumin (<3.5 g/dL), and 1 point each for multilobar infiltrates, RR ≥25 (or ≥30 age-adjusted), tachycardia ≥125 bpm, confusion, and low oxygenation. SMART-COP score ≥5 = high likelihood of IRVS. For emergency physicians, combining CURB-65 for initial risk stratification with ATS/IDSA severe CAP criteria for ICU threshold decisions is the most practical evidence-based approach.

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