The DECAF score categorizes COPD exacerbations by evaluating five clinical criteria to predict the risk of in-hospital mortality. Each criterion contributes a specific point value to the total score. 

The criteria and their corresponding scores are as follows:

- eMRCD Dyspnea Level:
  - eMRCD 1-4: 0 points
  - eMRCD 5a (too dyspneic to leave the house, but independent with washing/dressing): 1 point
  - eMRCD 5b (too dyspneic to leave the house, requires washing/dressing): 2 points

- Eosinopenia:
  - Yes (eosinophil count < 0.05×10⁹/L): 1 point
  - No: 0 points

- Consolidation on Chest X-ray:
  - Yes: 1 point
  - No: 0 points

- Moderate to Severe Acidemia:
  - Yes (pH < 7.3): 1 point
  - No: 0 points

- Atrial Fibrillation (past or present):
  - Yes: 1 point
  - No: 0 points

Each response is transformed into a score using the categories above. The overall DECAF score is the sum of these points, ranging from 0 to 6. Based on this score, the calculated risk of in-hospital mortality is interpreted as follows:

- A score of 0 corresponds to a low-risk group with 0% in-hospital mortality.
- A score of 1 still characterizes a low-risk group, showing a 1.5% mortality risk.
- A score of 2 indicates an intermediate risk with a 5.4% chance of mortality.
- A score of 3 identifies a high-risk group, raising the mortality risk to 15.3%.
- A score of 4 places the patient firmly in the high-risk category with a 31% mortality chance.
- A score of 5 increases the risk within this group to 40.5%.
- Finally, a score of 6 represents the highest risk group with a 50% chance of mortality.

This scoring system aids healthcare professionals in assessing COPD severity, guiding management decisions effectively in clinical settings.

The DECAF Score is a clinical calculator used for patients with Chronic Obstructive Pulmonary Disease (COPD). DECAF stands for Dyspnoea, Eosinopenia, Consolidation, Acidaemia, and atrial Fibrillation. This scoring system is used to predict the in-hospital mortality risk of patients admitted with acute exacerbations of COPD. 

The DECAF score is applicable to patients with a confirmed diagnosis of COPD who are experiencing an acute exacerbation severe enough to warrant hospital admission. It is not suitable for use in patients without a COPD diagnosis, those with stable COPD, or those with other primary causes of respiratory distress. The score helps clinicians to make informed decisions about the level of care required, including the need for intensive care admission.

DECAF score for COPD