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    CURB-65 Score for Pneumonia Severity

    Estimates mortality of community-acquired pneumonia to help determine inpatient vs. outpatient treatment.
    When to Use
    Why Use

    The CURB-65 calculator can be used in the emergency department setting to risk stratify a patient’s community acquired pneumonia.

    • The CURB-65 Score includes points for confusion and blood urea nitrogen, which in the acutely ill elderly patient, could be due to a variety of factors. An alternative scoring system, SOAR, circumvents those two parameters. It uses low systolic BP (S) and poor oxygenation (PaO2: FIO2) (O), advancing age (A), high respiratory rate (R).
    • CURB-65 does not assign points for co-morbid illness and nursing home residence, as the original study did account for many of these conditions.
    • CURB-65 may not identify patients requiring ICU admission as well as the PSI.
    • CURB-65 is fast to compute, requires likely already-available patient information, and provides an excellent risk stratification of community acquired pneumonia. It can facilitate better utilization of resources and treatment initiation.
    • In comparison to the PSI, CURB-65 offers equal sensitivity of mortality prediction due to community acquired pneumonia. Notably, CURB-65 (74.6%) has a higher specificity than PSI (52.2%).


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    Next Steps
    Creator Insights


    While many pneumonias are actually viral in nature, typical practice is to provide a course of antibiotics given the pneumonia may be bacterial.

    Disposition (inpatient vs. outpatient) often dictates further care and management -- including lab testing, blood cultures, etc.


    The CURB-65 scores range from 0 to 5. Assign points as in the table based on confusion status, urea level, respiratory rate, blood pressure, and age. Clinical management decisions can be made based on the score, as described in the validation study below:

    0 or 11.5% mortalityOutpatient care
    29.2% mortalityInpatient vs. observation admission
    ≥ 322% mortalityInpatient admission with consideration for ICU admission with score of 4 or 5

    Critical Actions

    For patients scoring high on CURB-65, it would be prudent to ensure initial triage has not missed the presence of sepsis. Evaluation of SIRS criteria would be beneficial.


    Addition of the selected points, as above.

    Facts & Figures

    Score interpretation (as per derivation study):

    CURB-65 scoreMortality RiskRecommendation per Derivation Study
    00.60%Low risk; consider home treatment
    12.70%Low risk; consider home treatment
    26.80%Short inpatient hospitalization or closely supervised outpatient treatment
    314.00%Severe pneumonia; hospitalize and consider admitting to intensive care
    4 or 527.80%Severe pneumonia; hospitalize and consider admitting to intensive care

    Evidence Appraisal

    The original study was a retrospective review of three prospective studies of CAP in the UK, New Zealand, and the Netherlands. It included a total of 1068 patients. A five-point score based on confusion, urea, respiratory rate, blood pressure, and age was developed to stratify patients into different treatment group based on mortality risk. The validation study was done in India and included 150 patients.

    CURB-65’s original study including co-morbidity variables like chronic lung disease, chronic liver disease, CHF, CVD, and DM, and these were controlled for when developing the relevant criteria for the risk stratification that ultimately led to CURB-65’s risk factors.

    Several other more recent validation studies in several different countries show increasing mortality and even need for intubation with increasing CURB-65 scores, ranging from 0-1.1% (CURB-65 score = 0) to 17-60% (CURB-65 score = 5), with over 3100 patients in these studies when combined.



    Research PaperShah BA, et. al. Validity of Pneumonia Severity Index and CURB-65 Severity Scoring Systems in Community Acquired Pneumonia in an Indian Setting. The Indian Journal of Chest Diseases & Allied Sciences. 2010;Vol.52.Research PaperAujesky D, Auble TE, Yealy DM, et al. Prospective comparison of three validated prediction rules for prognosis in community-acquired pneumonia. Am. J. Med. 2005;118(4): 384–92.doi:10.1016/j.amjmed.2005.01.006. PMID 15808136Research PaperMyint PK, Kamath AV, Vowler SL, Maisey DN, Harrison BD. Severity assessment criteria recommended by the British Thoracic Society (BTS) for community-acquired pneumonia (CAP) and older patients. Should SOAR (systolic blood pressure, oxygenation, age and respiratory rate) criteria be used in older people? A compilation study of two prospective cohorts. Age Ageing. 2006;35(3):286-91.Research PaperCapelastegui A, España PP, Quintana JM, et al. Validation of a predictive rule for the management of community-acquired pneumonia. Eur Respir J. 2006;27(1):151-7.
    Dr. John Macfarlane

    About the Creator

    John Macfarlane, MD, is a consultant respiratory physician at Nottingham City Hospital in the United Kingdom. He is an active researcher in the field of thoracic medicine with a special focus on bacterial and community acquired infections.

    To view Dr. John Macfarlane's publications, visit PubMed

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    Dr. John Macfarlane
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