CURB-65 / CRB-65 Pneumonia Severity Pathway

Admit or treat at home, and CRB-65 when there is no urea to han · v1.0
How to use this tool: Enter what you have. If a urea is available, the tool scores CURB-65 and gives a mortality-based admission recommendation. If it is not, tick "urea not available" and the tool falls back to CRB-65, built for exactly that situation. Neither score replaces clinical judgement: a young patient with a low score who looks unwell, or who cannot manage oral intake or care for themselves at home, should still be admitted.

1. Confusion and Age

2. Vitals

3. Urea (Blood Urea, Not BUN)

Most Indian lab slips report "Blood Urea" in mg/dL directly, not BUN. If your report says BUN, multiply by 2.14 to get blood urea in mg/dL before entering it, or switch the unit here if the report is already in mmol/L.

Clinical Disclaimer: CURB-65 and CRB-65 estimate 30-day mortality from community-acquired pneumonia. They do not account for hypoxaemia, decompensated comorbidity, social circumstances, or the patient's ability to take oral antibiotics reliably at home. Use the score to support a decision, not to make it.

Clinical Application & Nuances

1. CRB-65 Exists Because Urea Is Not Always Available

CURB-65 needs a same-day urea, which a primary health centre without a laboratory cannot always provide. CRB-65 drops urea and keeps the other four criteria, and was validated for exactly that setting: a clinician with a blood pressure cuff, a watch, and a bedside assessment of confusion. It is the tool for a district or rural practice where the choice is CRB-65 today or no score at all.

2. Blood Urea, Not BUN

The original criterion is urea above 7 mmol/L, which is 42 mg/dL of blood urea, not BUN. Indian laboratory reports overwhelmingly quote blood urea directly. A report quoting BUN needs multiplying by roughly 2.14 to become blood urea in mg/dL before it is compared with this threshold; using a BUN value directly against the 42 mg/dL line under-calls the score.

3. The Score Is a Floor, Not a Ceiling

A low score describes low mortality risk from the pneumonia itself. It says nothing about a patient who cannot swallow tablets reliably, lives alone with nobody to observe deterioration, or has an unstable comorbidity such as poorly controlled diabetes or ischaemic heart disease. Any of these can justify admission over a score that reads low.

4. What Indian Validation Has Found

A study from an Indian tertiary centre comparing CURB-65 against the Pneumonia Severity Index found CURB-65 simpler to apply at the bedside and broadly concordant with outcomes, while noting, as most validation cohorts do, that neither score alone should override a clinician's assessment of the individual patient in front of them.

5. This Tool Does Not Choose the Antibiotic

CURB-65 and CRB-65 answer "how sick is this pneumonia, and where should it be managed", not "which antibiotic". The Empirical Antimicrobial Pathway takes the severity and setting from here and works out the regimen.

Abbreviations: BP (Blood Pressure) · BTS (British Thoracic Society) · BUN (Blood Urea Nitrogen) · CAP (Community-Acquired Pneumonia) · ICU (Intensive Care Unit) · NICE (National Institute for Health and Care Excellence) · PHC (Primary Health Centre) · PSI (Pneumonia Severity Index)
Algorithm References & Evidence Base
  1. Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377-382.
  2. Lim WS, Baudouin SV, George RC, et al. BTS guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009;64(Suppl 3):iii1-iii55.
  3. National Institute for Health and Care Excellence. Pneumonia in adults: diagnosis and management. NICE guideline NG250. 2025.
  4. Ewig S, Torres A. Severity assessment in community-acquired pneumonia. Curr Opin Pulm Med. 2001;7(3):180-186.
  5. Chalmers JD, Singanayagam A, Akram AR, et al. Severity assessment tools for predicting mortality in hospitalised patients with community-acquired pneumonia: systematic review and meta-analysis. Thorax. 2010;65(10):878-883.
  6. Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia: an official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67.
  7. Shah BA, Ahmed W, Dhobi GN, Shah NN, Khursheed SQ, Haq I. Validity of pneumonia severity index and CURB-65 severity scoring systems in community acquired pneumonia in an Indian setting. Indian J Chest Dis Allied Sci. 2010;52(1):9-17.
  8. Gupta D, Agarwal R, Aggarwal AN, et al. Guidelines for diagnosis and management of community- and hospital-acquired pneumonia in adults: joint ICS/NCCP(I) recommendations. Lung India. 2012;29(Suppl 2):S27-S62.
How to Cite This Tool

AMA Style:
Umakanth S. CURB-65 / CRB-65 Pneumonia Severity Pathway. MEDiscuss. Published 2026. Accessed .

Vancouver Style:
Umakanth S. CURB-65 / CRB-65 Pneumonia Severity Pathway [Internet]. MEDiscuss.org; 2026 [cited ]. Available from:

Disclaimer and scope
Disclaimer: This decision-support system is written for healthcare professionals. It does not substitute clinical judgment, and the treating physician retains absolute responsibility for every diagnostic, dosing and therapeutic decision. The algorithms are built on the evidence as it stands, and the evidence moves. Verify the output against your current institutional protocol, and against the patient in front of you.
© 2026 MEDiscuss.org. All rights reserved. This CDSS Module was designed and developed by Dr Shashikiran Umakanth from the published evidence. Provided free of charge for clinical use. Unauthorised reproduction or redistribution is strictly prohibited. Keep this system on your phone's home screen
Category Therapeutic & Management PathwaysPathway
Specialties Internal Medicine, Pulmonology, Infectious Diseases
Written and maintained by Dr Shashikiran Umakanth.
Last revised: 23 August 2026
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