The CURB-65 score is a clinical tool healthcare professionals use to assess the severity of community-acquired pneumonia. Developed in 2002, its primary function is to predict mortality and guide decisions about patient care, such as determining the most appropriate treatment setting. This scoring system provides a standardized framework to support a doctor’s evaluation of a patient’s condition.
The CURB-65 Acronym Explained
CURB-65 is an acronym where each letter represents a specific clinical marker that contributes to a patient’s overall score. Each of these factors, when present, points to a greater severity of illness and an increased risk of mortality.
The “C” in the acronym stands for confusion. This refers to a new or worsening state of disorientation relative to the patient’s typical mental status. It is formally identified by an Abbreviated Mental Test (AMT) score of 8 or less. An acute change in mental state can be a serious sign that the pneumonia is affecting the entire body, potentially by reducing oxygen supply to the brain.
“U” represents urea, a waste product filtered from the blood by the kidneys. A blood urea nitrogen (BUN) level greater than 19 mg/dL (or urea > 7 mmol/L) signals that the kidneys may not be functioning properly. This can be a result of dehydration, which often accompanies severe illness, or indicate that the infection is causing broader organ stress.
The “R” signifies the patient’s respiratory rate. A rate of 30 breaths per minute or more is a clear indicator of respiratory distress. A healthy adult at rest typically breathes 12 to 20 times per minute, so a significantly faster rate shows the lungs are working much harder than normal to supply the body with enough oxygen.
“B” relates to blood pressure. Specifically, a systolic blood pressure below 90 mm Hg or a diastolic pressure of 60 mm Hg or less meets this criterion. Low blood pressure, or hypotension, is an alarming sign that can suggest the onset of sepsis. In this state, the body’s response to infection can cause blood vessels to dilate, leading to a dangerous drop in pressure and inadequate blood flow to organs.
Finally, the “65” refers to the patient’s age. Being 65 years or older is an independent factor in the CURB-65 score. Older adults often have a diminished immune response and may have other underlying health conditions, making them more vulnerable to severe complications from pneumonia.
Calculating and Interpreting the Score
The calculation of the CURB-65 score is straightforward. A patient receives one point for each of the five criteria they meet: Confusion, Urea > 19 mg/dL, Respiratory rate ≥ 30, low Blood pressure, and an age of 65 or older. This results in a final score from 0 to 5, with a higher score indicating more severe pneumonia and a greater risk of death.
The resulting score is stratified into three risk categories that guide clinical management. A score of 0 or 1 suggests a low risk of mortality, estimated at less than 2%. For these patients, treatment at home on an outpatient basis is generally considered safe and appropriate.
A score of 2 places the patient in a moderate-risk group, with a 30-day mortality risk rising to around 9%. These individuals typically require hospital admission for supervised treatment, which may include a short inpatient stay and close monitoring.
Patients with a score of 3 or higher are classified as high risk. The mortality rate for this group reaches 17% for a score of 3 and as high as 41.5% for a score of 4. Urgent hospitalization is necessary for these patients, and those with scores of 4 or 5 should be assessed for admission to an intensive care unit (ICU).
Clinical Purpose of the CURB-65 Score
The CURB-65 score serves a distinct purpose in clinical practice, particularly in environments like emergency departments. It provides a rapid, objective, and standardized method for assessing pneumonia severity. This consistency helps ensure all patients are evaluated against the same criteria, reducing variability in care decisions.
By quantifying the 30-day mortality risk, the tool helps clinicians make informed decisions about resource allocation. It assists in determining which patients require a hospital bed versus who can be managed in the community. This prioritization is useful when healthcare resources are limited.
The CURB-65 score is designed to aid, not replace, a physician’s professional judgment. Other factors, such as coexisting illnesses, social support at home, and the patient’s ability to take oral medications, also influence the final treatment plan. The score is one of several tools that contribute to a comprehensive clinical evaluation.