The COPD Assessment Test (CAT) is designed to measure the impact of chronic obstructive pulmonary disease on a person's daily life. It involves responding to eight items about symptoms and limitations. For each question, the participant selects an answer from a predefined scale, which is converted to a numerical score.

The scoring system assigns values as follows:

- Cough: 
  - "I never cough" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "I cough all the time" = 5
- Phlegm:
  - "I have no phlegm in my chest at all" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "My chest is completely full of phlegm" = 5
- Chest tightness:
  - "My chest does not feel tight at all" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "My chest feels very tight" = 5
- Breathlessness:
  - "When I walk up a hill or one flight of stairs I am not breathless" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "When I walk up a hill or one flight of stairs I am very breathless" = 5
- Activities:
  - "I am not limited doing any activities at home" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "I am very limited doing any activities at home" = 5
- Confidence:
  - "I am confident leaving my home despite my lung condition" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "I am not at all confident leaving my home because of my lung condition" = 5
- Sleep:
  - "I sleep soundly" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "I don't sleep soundly because of my lung condition" = 5
- Energy:
  - "I have lots of energy" = 0
  - "1" = 1
  - "2" = 2
  - "3" = 3
  - "4" = 4
  - "I have no energy at all" = 5

To calculate the total score, simply add the numerical values for each response. This score can range from 0 to 40.

The interpretation of the score reflects the health impact of COPD:
- A score from 0 to 10 suggests a "Low health impact."
- A score from 11 to 20 suggests a "Medium health impact."
- A score from 21 to 30 suggests a "High health impact."
- A score from 31 to 40 suggests a "Very high health impact."

This provides a straightforward way to assess how COPD affects an individual's life across different areas, making it easier to identify where additional management might be needed.

The COPD Assessment Test (CAT) is a clinical calculator used specifically for patients with Chronic Obstructive Pulmonary Disease (COPD). This scoring system is designed to measure the impact of COPD on a person's life, and how this changes over time. It is a patient-completed instrument that helps to quantify the impact of COPD symptoms on health status. The CAT score is used to guide treatment decisions, assess disease progression, and evaluate the effectiveness of treatments in COPD patients. It is not suitable for use in patients without a confirmed diagnosis of COPD or in those with other respiratory disorders as it is specifically designed for COPD.