Toolbox - CRB65
GP and London Respiratory Team lead Dr Noel Baxter discusses this useful tool for recognition and management of life threatening community-acquired pneumonia.
The CRB65 score is a mortality prediction tool for use by community clinicians making an initial assessment of people with suspected community-acquired pneumonia (CAP).1,2,3 It is similar to the CURB65 used in hospital environments but does not include an assessment of urea.4,5
The clinical point scoring system provides clinicians with a measure of low (0), intermediate (1,2) or high (3,4) risk of mortality at 30 days. The aim is to help reduce amenable mortality caused by CAP by ensuring that those at higher risk of mortality are admitted to hospital.
Calculating the score
|Confusion||Abbreviated mental test* score ≤ 8||1|
Systolic < 90 mmHg or
Diastolic ≤ 60 mmHg
*Age, recognition of two persons (e.g. doctor, nurse), DOB, address recall (e.g. 42 West Street), time, date of first or second world war, year, monarch, surgery name, count backwards 20 ➔ 1
Acting on the score
|Score||Risk of mortality||Action|
|0||Low||Manage with local antibiotic protocol|
|1,2||Intermediate||Closely monitor response with low threshold for admission|
|3,4||High||Call 999. Admit urgently and commence antibiotics before transfer. Risk of death increases with each hour.|
Who is it for?
CAP accounts for 5-12% of GP-diagnosed lower respiratory tract infection requiring antibiotics.6 An average practice with 10,000 patients will see about 50-110 cases of CAP per year and less than half of these will need hospitalisation. It can be a challenge to diagnose and manage CAP in primary care because the gold standard test in secondary care – a chest X-ray - is generally not available or recommended in community management.7
As the name suggests, the CRB65 is a tool that is most likely to be used on older patients – anyone aged 65 or over with suspected CAP immediately scores one point. But the test has been validated in patients under 65 and so its use in younger people with suspected LRTI and additional risk factors is recommended.8
Factors associated with worse outcomes in respiratory infection include hospitalisation in the last year, diabetes, heart failure and use of oral steroids.7,9,10 Older patients often have fewer respiratory symptoms but more noticeable systemic symptoms such as lethargy or loss of appetite.11 It is during this part of the assessment that confusion – the ‘C’ in CRB65 - should become apparent in the more severe cases. The examination tool recommended to assess confusion in this situation is the Abbreviated Mental Test12 - a result of eight or less on this test adds one point to the CURB65 score.
Routine vital sign collection in a suspected LRTI, or indeed in any acutely unwell patient, can alert you to more severe illness and includes pulse, respiratory rate, blood pressure, temperature, and pulse oximetry. For example, a finding of tachypnea and hypotension would accrue two points.
A newer alternative to CRB65 is being trialled which involves use of pulse oximetry in addition to other parameters, but the tool is not currently validated in primary care.3
CRB65 has been extensively validated but mostly in hospital-assessed cases where mortality and intensive care requirements are significantly higher than CAP management initiated in the community. A 2010 systematic review of 14 studies where only one study was performed entirely in primary care showed that the CRB65 rule was a good risk predictor for mortality within 30 days when used in a hospital setting but when performed in the community there was significant over-prediction of risk for mortality especially in those within the intermediate risk group (scores 1,2).8 This might have economic implications as unnecessary admissions could arise from the actions suggested for this group that require further clinical judgement.
Dr Noel Baxter is a GP in south London and co-lead of the London Respiratory Team and executive member of PCRS-UK.
Dr Baxter would like to thank Dr Steve Holmes for his help in reviewing this article.
The Primary Care Respiratory Society UK (PCRS-UK) is the UK-wide professional society dedicated to meeting the vision of “optimal respiratory care for all.” Our mission is to give every member of the primary care practice team the confidence to deliver quality respiratory care, improve the quality of life for patients with respiratory disease.
1. BAUER TT, Ewig S, MARRE, R et al. CRB65 predicts death from community-acquired pneumonia. Journal of Internal Medicine, 2006;260(1):93-101
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3. Ochoa-Gondar O, Vila-Corcoles A, Rodriguez-Blanco T et al. Comparison of three predictive rules for assessing severity in elderly patients with CAP. Int J Clin Pract, 2011 Nov;65(11):1165-72. PubMed PMID: 21951687. Epub 2011/09/29. eng.
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8.McNally M, Curtain J, O’Brien KK et al. Validity of British Thoracic Society guidance (the CRB65 rule) for predicting the severity of pneumonia in general practice: systematic review and meta-analysis. British Journal of General Practice. 2010 //;60(579):e423-e33.
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12. Hodkinson HM. Evaluation of a mental test score for assessment of mental impairment in the elderly. Age and Ageing. 1972 November 1, 1972;1(4):233-8