CURB-65 Score for Pneumonia Severity

Community acquired pneumonia (CAP) is a common condition that presents in the outpatient setting (primary care and emergency care) with a hospitalization rate of approximately 2% in ages ≥ 65 years and is associated with a 30-day mortality rate of 5% in hospitalized patients (Womack & Kropa, 2022). Further, Womack & Kropa highlight that in 11% of patients a bacterial pathogen was identified, 23% of patients a viral pathogen and 62% of patients no organism was identified. (Note: These studies were conducted before the COVID-19 pandemic.) Diagnosis of community acquired pneumonia (CAP) is usually made with a combination of history, physical exam, and findings on chest x-ray, lung US or chest CT scan. Clinicians are encouraged to use both their clinical judgement and a validated clinical prediction rule to determine the need for hospitalization in patients with CAP (Armstrong, 2020). The CURB-65 (confusion, urea level, respiratory rate, blood pressure, and age 65 or older) Score for pneumonia severity is a well-validated risk stratification tool that can assist clinicians in the outpatient setting with determining disposition (inpatient versus outpatient) and does not require laboratory testing. 

However, validated clinical prediction rules, like the CURB-65 and Pneumonia Severity Index (PSI), do not effectively determine the level of care required (Armstrong, 2020). The American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) criteria for severe CAP is preferred to predict ICU admission.¹ Low-quality evidence suggests the PSI may outperform CURB-65. Armstrong (2020) reports the PSI can underestimate the severity of illness among younger patients, but it has higher discriminative power in predicting mortality and a lover false-positive rate then the CURB-65.

¹Statement on COVID-19 (Armstrong, 2020): "Editor's Note: This ATS/IDSA guideline was produced before the COVID-19 pandemic, which has altered the diagnosis and management of lower respiratory tract infections. The current version of this guideline limits testing and antiviral treatment in patients with influenza, and we expect testing for and treatment of severe acute respiratory syndrome coronavirus 2 infection to become a long-standing element of standard pneumonia care. 

• Although the IDSA has published initial guidelines for management of COVID-19, the situation is evolving rapidly (https://www.idsociety.org/practice-guideline/covid-19-guideline-treatment-and-management).
• Free information on COVID-19 is available from American Family Physician at https://www.aafp.org/journals/afp/explore/COVID-19.html and Essential Evidence Plus at http://www.essentialevidenceplus.com/content/eee/904."

The CURB-65 Score (confusion, urea level, respiratory rate, blood pressure, and age 65 or older) for pneumonia severity is a well-validated risk stratification tool that can assist clinicians in the outpatient setting with determining disposition (inpatient versus outpatient) and does not require laboratory testing. 

Rule criteria

Scoring & Recommendations* 

*Risk groups and score cut-offs based on the derivation study performed by Lim et al (2003).

Considerations

According to the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) practice guidelines on patients with community acquired pneumonia (CAP)(Armstrong, 2020; Womack & Kropa, 2022):

• Clinical judgement is a key component to determine the need for hospitalization.
• Validated clinical prediction rules, like the Curb-65 and Pneumonia Severity Index (PSI), do not effectively determine the level of care required.
• The ATS/IDSA criteria for severe CAP is preferred to predict ICU admission.¹
• Five-day antibiotic treatment courses are recommended for all patients with CAP, with reassessment following treatment.
• For outpatients without comorbidities, treatment with amoxicillin, doxycycline or macrolide is recommended.
• Routine treatment of CAP with macrolide monotherapy is no longer recommended unless local resistance is low (< 25%). 
• In outpatients with comorbidities and inpatients with non-severe pneumonia, a combination of a beta-lactam or third-generation cephalosporin plus a macrolide, or monotherapy with a respiratory fluoroquinolone is recommended. 
• Patients should be treated for methicillin-resistant Staphylococcus aureus or Pseudomonas infection only if they present with risk factors for those pathogens.

¹Statement on COVID-19 (Armstrong, 2020): "Editor's Note: This ATS/IDSA guideline was produced before the COVID-19 pandemic, which has altered the diagnosis and management of lower respiratory tract infections. The current version of this guideline limits testing and antiviral treatment in patients with influenza, and we expect testing for and treatment of severe acute respiratory syndrome coronavirus 2 infection to become a long-standing element of standard pneumonia care. 

• Although the IDSA has published initial guidelines for management of COVID-19, the situation is evolving rapidly (https://www.idsociety.org/practice-guideline/covid-19-guideline-treatment-and-management). 
• Free information on COVID-19 is available from American Family Physician at https://www.aafp.org/journals/afp/explore/COVID-19.html and Essential Evidence Plus at http://www.essentialevidenceplus.com/content/eee/904."

• Diagnosis of community acquired pneumonia (CAP) is usually made with a combination of history, physical exam, and findings on chest x-ray, lung US or chest CT scan.
• Intended for immunocompetent adults who have not recently traveled internationally.