What is the COPD Assessment Test (CAT)?
The COPD Assessment Test (CAT) is a short, validated 8-item questionnaire designed to comprehensively assess the impact of COPD on a patient's health status, going beyond simple breathlessness to capture the full symptom burden of the disease. 1
Purpose and Clinical Use
The CAT was developed because COPD impacts patients well beyond dyspnea alone, and comprehensive symptom assessment is essential for proper disease management 1. Unlike longer, more complex health status questionnaires (such as the St. George's Respiratory Questionnaire or Chronic Respiratory Questionnaire), the CAT is practical enough for routine clinical use 1.
Key Clinical Applications:
- Symptom burden assessment: Quantifies the overall impact of COPD symptoms on daily life
- Treatment guidance: Helps determine appropriate therapeutic interventions based on symptom severity
- Risk stratification: Predicts exacerbations, depression, acute health status deterioration, and mortality 2
- Treatment response monitoring: Demonstrates responsiveness to interventions, with typical improvements of 2.2-3 units following pulmonary rehabilitation 3
Scoring and Interpretation
The critical threshold is a CAT score of 10, which separates patients with lower versus higher symptom burden 1. This cutoff point is equivalent to an SGRQ score of ≥25 1.
Score Categories:
- <10: Lower symptom burden
- ≥10: Higher symptom burden requiring more intensive symptom management
The CAT demonstrates strong psychometric properties with internal consistency of 0.85-0.98 and test-retest reliability of 0.80-0.96 3. The minimum clinically important difference (MCID) is approximately 2 units 3.
Clinical Correlations
CAT scores correlate significantly with disease severity and clinical outcomes:
- Strong negative correlation with FEV1% predicted (r = -0.55, p<0.001) 4
- Scores increase proportionally with GOLD severity stages 5, 4
- Frequent exacerbators have significantly higher baseline CAT scores (19.5 vs 16.8, p=0.025) 6
- CAT scores rise by an average of 4.7 units at exacerbation onset 6
- Correlates with number of exacerbations, healthcare visits, and hospitalization days 5
Integration into COPD Assessment
According to GOLD guidelines, comprehensive COPD assessment requires evaluating three separate components 1:
- Spirometric severity (airflow limitation)
- Symptom burden (using CAT or mMRC)
- Exacerbation risk (history of previous events)
The CAT serves as the preferred tool for component #2 because it captures the multidimensional nature of COPD symptoms more comprehensively than simple breathlessness scales like the mMRC 1.
Important Caveats
- CAT is NOT a diagnostic tool - spirometry remains essential for COPD diagnosis 1
- CAT and mMRC are not interchangeable: Despite both having recommended cutoffs (CAT ≥10 vs mMRC ≥2), agreement between these tools ranges from κ=0.13 to 0.77, with an average 13% difference in patient classification 2
- CAT scores can only explain <50% of variance in predictive models, indicating other factors influence health status 2
- The tool is responsive to treatment changes, showing significant improvement (mean -2.4 points) after 12 months of appropriate therapy 5
Practical Clinical Value
Use the CAT at every clinical encounter to monitor symptom burden consistently and tailor treatment accordingly, as substantial proportions of patients on bronchodilator therapy still experience high symptom burden that negatively affects health status 7. The CAT provides actionable information for treatment escalation or de-escalation decisions in the closed-loop management approach recommended by current guidelines 8.