COPD Assessment Test Calculator
Score the eight CAT questions from 0 to 5 and see the total, impact band, and meaningful change threshold.
What it does
The COPD Assessment Test, usually called CAT, is an eight item symptom questionnaire for people with chronic obstructive pulmonary disease. It measures how much cough, phlegm, chest tightness, breathlessness, activity limitation, confidence, sleep, and energy affect daily life. The total runs from 0 to 40.
Each question uses a six point scale from 0 to 5. The person chooses the statement that best matches how they feel now, not how they felt months ago. The eight answers are added. Higher totals mean a heavier symptom burden. The test does not measure lung function and does not replace spirometry.
The usual bands are 0 to 9 for low impact, 10 to 20 for medium impact, 21 to 30 for high impact, and 31 to 40 for very high impact. Some clinics use the bands to guide conversations about inhalers, pulmonary rehabilitation, and action plans. The score is also used to track response to treatment.
A change of 2 points or more is generally considered clinically meaningful. A drop of 2 points can be a real improvement even when the total remains in the same band. A rise of 2 points can signal a flare, a new comorbidity, or a decline in activity. The threshold is a guide, not a hard line for every patient.
CAT is short enough to complete in the waiting room and can be repeated at each visit. It is not a diagnostic test. A person without COPD can also have a high score from asthma, heart failure, obesity, or deconditioning. Use the score with the clinical history, spirometry, exacerbation history, and the patient's own goals.
How to use
- Ask the person to answer for how they feel right now, not for a better day or a worse day.
- Read each question and its six statements. Let the person choose one statement per question.
- Score each answer from 0 to 5. Do not skip questions, because a missing item changes the total.
- Add the eight scores. The result is the CAT total from 0 to 40.
- Match the total to the impact band and compare it with the previous score when one exists.
- Record the total and the date. Repeat at follow up, after an exacerbation, or after a change in treatment.
Formula
- Items
- Eight questions covering cough, phlegm, chest tightness, breathlessness, activity, confidence, sleep, and energy.
- Item score
- A value from 0 to 5 chosen from six statements for each question.
- Total
- Sum of the eight items, from 0 to 40.
- Change
- A difference of 2 points or more between visits is usually treated as meaningful.
The CAT is scored by simple addition, with no weighting. All eight items count equally. A person who leaves an item blank should be asked to complete it rather than having the missing value treated as zero. The bands are descriptive, not a diagnosis. The test asks about current symptoms, so a recent infection or a bad night can raise the score. Repeat when the person is stable to get a fair baseline.
Worked example
Example: total 17, medium impact
A patient rates cough 3, phlegm 2, chest tightness 3, breathlessness on stairs 2, activity limitation 2, confidence leaving home 1, sleep 2, and energy 2.
- Cough: 3 and phlegm: 2.
- Chest tightness: 3.
- Breathlessness on stairs: 2.
- Activity limitation: 2.
- Confidence leaving home: 1, sleep: 2, and energy: 2.
- Add: 3 + 2 + 3 + 2 + 2 + 1 + 2 + 2 = 17.
- A total of 17 is between 10 and 20, so the impact band is medium.
Reference table
| Total | Impact | Typical use |
|---|---|---|
| 0 to 9 | Low | Few symptoms, routine review |
| 10 to 20 (worked: 17) | Medium | Review treatment and activity |
| 21 to 30 | High | Intensify treatment and rehabilitation |
| 31 to 40 | Very high | Urgent review and intensive support |
Limits
- CAT measures symptoms, not airflow obstruction. A normal score does not exclude COPD and a high score does not confirm it.
- Other conditions such as heart failure, asthma, obesity, and depression can raise the score.
- The test depends on the person's interpretation of the statements, so scores can vary between visits.
- A single score cannot show whether a treatment worked. Change matters more than one number.
Common mistakes
- Scoring a missing item as zero instead of asking the person to complete it.
- Using the score to diagnose COPD without spirometry.
- Comparing scores taken during an exacerbation with scores taken when stable.
- Treating a 1 point change as meaningful when the usual threshold is 2 points.
- Ignoring the pattern of answers, such as severe breathlessness with low cough, which may suggest another cause.
Try it yourself
Quick checks. Answers sit tucked under each question.
All eight items are 0. What is the total and band?
0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 = 0. The total is 0, which is low impact.
All eight items are 5. What is the total and band?
8 x 5 = 40. The total is 40, which is very high impact.
The eight scores are 5, 5, 5, 5, 1, 0, 0, and 0. What is the total and band?
5 + 5 + 5 + 5 + 1 + 0 + 0 + 0 = 21. The total is 21, which is high impact.
Questions
What is a normal CAT score?
There is no single normal value. A total of 0 to 9 is low impact. A lower score is generally better.
What change is meaningful on CAT?
A difference of 2 points or more between visits is usually treated as clinically meaningful.
Does CAT diagnose COPD?
No. Diagnosis needs spirometry and clinical assessment. CAT measures how symptoms affect daily life.
How often should CAT be repeated?
Many clinics repeat it at each routine visit, after an exacerbation, or after a treatment change.
Can CAT be used in asthma?
It was designed for COPD. Asthma has its own control tests, such as the Asthma Control Test, so use the tool that matches the condition.
Why does my score change between visits?
Symptoms vary with infection, weather, activity, sleep, and mood. A change of 2 points or more is more likely to reflect a real shift than a 1 point change.