CURB-65 & qSOFA Calculator

About the CURB-65 & qSOFA Calculator

Enter a patient’s age, breathing rate, blood pressure and mental state once, and get three bedside scores:

• CURB-65 — Confusion, Urea over 7 mmol/L, Respiratory rate 30 or more, low Blood pressure, age 65 or more — the severity score for community-acquired pneumonia that NICE uses in hospital;
• CRB-65 — the same without urea, which NICE uses in primary care, where a blood result is not to hand;
• qSOFA — respiratory rate 22 or more, altered mentation and systolic pressure 100 mmHg or less, the Sepsis-3 prompt for patients with suspected infection.

Each score comes with the risk group and place-of-care options in NICE guideline NG250, or what the source study found. Urea can be entered in mmol/L, as blood urea nitrogen (BUN, mg/dL) or as urea in mg/dL. Written for clinicians; nothing leaves your browser.

Common uses

• Grading pneumonia severity at the front door and documenting why a patient is admitted or sent home.
• Scoring CRB-65 in a GP surgery, care home or on a home visit, where no blood test is available.
• Checking a patient with suspected infection for the qSOFA prompt alongside the pneumonia score.
• Converting a BUN or a urea in mg/dL against the CURB-65 threshold of 7 mmol/L.

The criteria

• CURB-65, 1 point each: Confusion — abbreviated Mental Test score 8 or less, or new disorientation in person, place or time · Urea over 7 mmol/L · Respiratory rate 30 breaths per minute or more · Blood pressure: systolic below 90 mmHg or diastolic 60 mmHg or less · age 65 or more. Range 0–5.
• CRB-65: the same without urea. Range 0–4.
• qSOFA, 1 point each: respiratory rate 22 per minute or more · altered mentation (Glasgow Coma Scale below 15) · systolic blood pressure 100 mmHg or less. 2 or more is positive.

Risk groups and place of care (NICE NG250)

• CRB65 in primary care (risk of death within 30 days): 0 low, less than 1% · 1 or 2 intermediate, 1% to 10% · 3 or 4 high, more than 10%. NICE suggests considering referral to hospital at 2 or more; at 1, primary care-led services with safety-netting advice or referral to a virtual ward, same-day emergency care (SDEC) unit, hospital at home service or hospital; at 0, primary care-led services with safety-netting advice.
• CURB65 in hospital: 0 or 1 low, less than 3% mortality risk · 2 intermediate, 3% to 15% · 3 to 5 high, more than 15%. NICE suggests considering inpatient care (with referral to critical care if appropriate) at 3 or more; at 2, a virtual ward, SDEC unit, hospital at home service or inpatient care; at 0 or 1, discharge home with referral to primary care-led services and safety-netting advice.
• NICE asks for clinical judgement alongside the score, bearing in mind that comorbidities or pregnancy can affect it, and for referral of anyone with signs of a more serious illness such as sepsis.
• In the study that developed CURB-65 (1,068 adults admitted with pneumonia), 30-day mortality was 0.7% with a score of 0 and rose to 57% with a score of 5.

qSOFA and sepsis screening

Sepsis-3 defines sepsis as life-threatening organ dysfunction caused by a dysregulated response to infection, shown by a rise in the SOFA score of 2 points or more. qSOFA is a bedside prompt for adults with suspected infection outside intensive care: in its derivation data, encounters outside the ICU with a qSOFA of 2 or more had a 3- to 14-fold increase in hospital mortality across levels of baseline risk.

qSOFA is not a screening test on its own. The Surviving Sepsis Campaign recommends against using it, compared with SIRS, NEWS or MEWS, as a single screening tool for sepsis or septic shock, because it is more specific but less sensitive: a qSOFA below 2 does not rule sepsis out.

Urea, BUN and the 7 mmol/L threshold

Labs report the same test in different ways. Urea in mmol/L (UK, Europe, Australia) is used as it is. Blood urea nitrogen (BUN) in mg/dL (US) measures only the nitrogen in urea: mmol/L = mg/dL ÷ 2.801. Urea in mg/dL (common in India and South Asia) measures the whole molecule: mmol/L = mg/dL ÷ 6.006. So the CURB-65 threshold of 7 mmol/L is a BUN of 19.6 mg/dL or a urea of 42 mg/dL.

Sources

• NICE guideline NG250, Pneumonia: diagnosis and management — boxes 1 and 2, recommendations 1.2.1–1.2.9
• Lim WS et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study
• Bauer TT et al. CRB-65 predicts death from community-acquired pneumonia
• Singer M et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) · Seymour CW et al. Assessment of clinical criteria for sepsis
• Evans L et al. Surviving Sepsis Campaign: international guidelines for management of sepsis and septic shock — recommendation 2

Limitations

• For adults: CURB-65 and CRB-65 grade community-acquired pneumonia, and qSOFA applies to suspected infection. For children NICE advises referral or specialist paediatric advice instead.
• The scores grade risk; they do not diagnose pneumonia or sepsis. NICE also refers anyone with signs of a more serious illness, such as sepsis, and considers referral for people who cannot take oral medicines, whatever the score.
• Mortality figures describe groups in the source studies and guidelines, not one patient.
• qSOFA below 2 does not rule out sepsis; follow your local sepsis screening tool (for example NEWS).

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