Pneumonia is a potentially serious infection that inflames the air sacs in one or both lungs. It can be caused by bacteria, viruses, or fungi, and can lead to symptoms such as cough, fever, chest pain, and difficulty breathing. While some cases are mild and resolve with rest and antibiotics, others can be life-threatening—especially in older adults, people with weakened immune systems, and those with chronic health conditions such as heart disease, diabetes, or chronic lung disease.
Assessing the severity of pneumonia is a critical step in medical decision-making. An accurate severity assessment helps healthcare providers determine the best treatment strategy, whether it's safe for the patient to recover at home or if they need to be hospitalized or admitted to intensive care. This is especially important in busy clinical settings or emergency departments, where fast and reliable evaluation tools can significantly impact patient outcomes.
To assist with this, standardized scoring systems such as CRB-65 and CRBU-65 have been developed. These tools help simplify the clinical evaluation process and ensure that important signs of deterioration are not missed.
The CRB-65 and CRBU-65 scoring systems are widely used to assess the severity of community-acquired pneumonia in adults. They are easy-to-use tools based on simple clinical observations that can be made at the bedside or in a primary care setting. These scores are designed to estimate the risk of mortality and help guide decisions about whether a patient requires hospital admission, urgent treatment, or can be managed safely at home.
The CRB-65 score is based on four key factors:
The CRBU-65 score includes all of the CRB-65 elements, with an additional criterion:
Each positive criterion scores one point. The total score helps clinicians estimate the severity of the pneumonia and the likelihood of mortality, and in turn, choose the right care pathway. A score of 0 suggests low risk, and the patient may be treated at home. A higher score indicates a need for closer monitoring, hospitalization, or intensive care, depending on the total.
Overall, CRB-65 and CRBU-65 scores are valuable tools in providing safe, efficient, and appropriate care for pneumonia patients. They enable standardized assessments, reduce guesswork, and help ensure that patients receive the level of care that best matches the seriousness of their condition.
The CRB-65 score is a simple and effective clinical tool used to assess the severity of community-acquired pneumonia in adult patients. It helps healthcare professionals quickly evaluate the risk of complications or death and decide whether the patient needs hospitalization or can be safely treated at home. The score is especially useful in primary care and emergency settings due to its ease of use and reliance on basic clinical observations.
The CRB-65 score evaluates four key indicators that are commonly associated with severe pneumonia or poor patient outcomes. Each indicator contributes one point to the total score. The higher the score, the greater the risk of mortality and the need for hospital-based care.
The CRB-65 scoring system is based on the following four criteria:
This refers to new-onset confusion or disorientation, which can be a sign that the infection is affecting the brain or that oxygen levels in the body are dangerously low. Confusion is usually assessed through questions about the patient’s awareness of time, place, and person. If confusion is present, 1 point is added to the score.
The respiratory rate is the number of breaths a person takes per minute. A rate of 30 or more breaths per minute is considered high and may indicate respiratory distress or reduced lung function due to pneumonia. If this threshold is reached or exceeded, 1 point is added to the score.
Low blood pressure is a sign that the body may be struggling to maintain proper circulation. Specifically, the score looks at a systolic blood pressure of 90 mmHg or lower, or a diastolic pressure of 60 mmHg or lower. If either condition is met, it suggests a risk of shock or organ failure, and 1 point is added to the score.
Age is an important risk factor for pneumonia complications. Individuals who are 65 years or older are more vulnerable to severe illness and have a higher risk of death. If the patient is 65 or older, 1 point is added to the CRB-65 score.
Each positive criterion adds 1 point, for a maximum score of 4. Based on the total score, healthcare providers can make informed decisions about the level of care required:
The CRBU-65 score is an extended version of the CRB-65 scoring system, designed to provide a more detailed assessment of pneumonia severity by including an additional laboratory parameter—uremia. This score is especially useful in hospital settings where blood test results are readily available. Like CRB-65, it helps clinicians evaluate the risk of serious outcomes in patients with community-acquired pneumonia and guides decisions on treatment and hospitalization.
The key difference between CRB-65 and CRBU-65 is the inclusion of uremia, which refers to an elevated level of urea (a waste product) in the blood. In the context of pneumonia, high urea levels may indicate dehydration, poor kidney function, or more severe illness overall. The specific threshold used in the CRBU-65 score is a blood urea level of greater than 7 mmol/l. If this condition is met, 1 point is added to the score.
Uremia is assessed through a blood test, so this criterion can only be applied when laboratory facilities are available. Its inclusion helps improve the accuracy of the severity assessment, especially in hospitalized patients who may be experiencing multiple organ involvement.
While both scores include the same four clinical criteria—confusion, respiratory rate, blood pressure, and age—the CRBU-65 adds one more layer of insight by considering kidney function. Here’s a quick comparison:
| Criterion | Included in CRB-65 | Included in CRBU-65 |
|---|---|---|
| Confusion | ✔ | ✔ |
| Respiratory Rate ≥ 30/min | ✔ | ✔ |
| Blood Pressure ≤ 90/60 mmHg | ✔ | ✔ |
| Age ≥ 65 years | ✔ | ✔ |
| Uremia > 7 mmol/l | ✖ | ✔ |
The CRBU-65 score ranges from 0 to 5 points. A higher score reflects an increased risk of mortality and suggests the need for more intensive monitoring and treatment. It’s especially valuable in hospital settings where more detailed diagnostics are available, and it provides a more complete picture of the patient’s condition than CRB-65 alone.
The CRB-65 and CRBU-65 Scores Calculator is designed to help users quickly assess the severity of community-acquired pneumonia based on simple clinical inputs. It is user-friendly and does not require any medical expertise to operate, although it is primarily intended for use by healthcare professionals. Follow the steps below to understand how to use the calculator effectively.
The calculator allows you to input five key indicators by simply checking a box next to each one:
You can select any combination of these checkboxes based on the patient's current status. Each selected item contributes one point to the final score.
Once you've selected the relevant checkboxes and clicked "Calculate," the calculator will display two results:
Here’s how to interpret the results:
| Score | Risk Level | Recommended Action |
|---|---|---|
| 0 | Low | Patient may be treated at home with close monitoring. |
| 1–2 | Moderate | Consider hospital referral for further evaluation and treatment. |
| 3–4 (CRB-65) or 3–5 (CRBU-65) | High | Urgent hospital admission is advised; intensive care may be required. |
Always consider the full clinical picture along with the score. The calculator is a helpful guide but does not replace professional medical judgment. If in doubt, consult a physician or specialist for further evaluation.
After using the calculator, you'll receive two results: the CRB-65 score and the CRBU-65 score. Each score provides a quick estimate of the patient’s risk level based on their clinical condition. The scores range from 0 (least severe) to 4 for CRB-65 and up to 5 for CRBU-65 if uremia is included. Understanding what these scores mean is essential for making appropriate decisions about patient care.
Each criterion in the scoring system contributes one point to the total score. The final score reflects the patient’s risk of complications or death from pneumonia:
| Score | Severity Level | Mortality Risk |
|---|---|---|
| 0 | Low | Very low risk of mortality |
| 1–2 | Moderate | Increased risk – requires clinical judgment |
| 3–4 (CRB-65) / 3–5 (CRBU-65) | High | Significantly increased risk – urgent care needed |
In general, the higher the score, the more severe the pneumonia and the greater the need for advanced medical intervention.
The score should be used as a guide to help decide the level of care needed. Below are the typical recommendations based on the total score:
The main difference is that CRBU-65 includes an additional criterion: uremia (blood urea level > 7 mmol/l). While CRB-65 uses only clinical signs—confusion, respiratory rate, blood pressure, and age—CRBU-65 adds a lab-based value to provide a more detailed assessment, typically used in hospital settings where blood tests are available.
This calculator is primarily intended for use by healthcare professionals. While it's simple to use, interpreting the results and making clinical decisions should be done by someone with medical training. However, patients and caregivers may use it for educational purposes or to discuss concerns with a healthcare provider.
If the calculator shows a score of 3 or more, it suggests a high risk of complications. In such cases, the patient should be evaluated by a medical professional immediately. High scores may require hospital admission or even intensive care.
The CRB-65 and CRBU-65 scores are useful tools, but they are not perfect. They are most accurate for assessing adults with community-acquired pneumonia. They may not fully capture the risk in younger patients, those with underlying health conditions, or those with hospital-acquired infections. Clinical judgment is always important.
Lab results are only needed if you want to calculate the CRBU-65 score, which includes blood urea levels. The CRB-65 score can be calculated without any lab tests, using only basic observations and patient information.
No, this tool does not diagnose pneumonia. It is used after a pneumonia diagnosis has been made to assess how severe the illness is. If you suspect you or someone else has pneumonia, seek medical evaluation for a proper diagnosis.
A score of 0 suggests a low risk of severe illness or death. In most cases, patients with a score of 0 can be treated safely at home with appropriate follow-up. However, other clinical factors should still be considered.
Yes. If a patient’s symptoms worsen or new signs appear (such as confusion or low blood pressure), the score should be recalculated. Monitoring changes in the CRB-65 or CRBU-65 score over time can help guide ongoing treatment decisions.
The CRB-65 and CRBU-65 Scores Calculator is provided for informational and educational purposes only. It is intended to assist healthcare professionals in assessing the severity of community-acquired pneumonia but is not a substitute for professional medical judgment, diagnosis, or treatment.
Always consult a qualified healthcare provider for any medical concerns or decisions. The calculator does not provide medical advice and should not be used by non-professionals to make health decisions for themselves or others. Scores generated by this tool should be interpreted in the context of a complete clinical evaluation, including physical examination, medical history, laboratory tests, and other relevant factors.
While every effort has been made to ensure the accuracy of this calculator, the developers and publishers are not responsible for any errors, omissions, or outcomes resulting from the use of this tool. Use of this calculator is at your own risk.