The COPD Assessment Test: What Do We Know So Far? A Systematic Review and Meta-Analysis About Clinical Outcomes Prediction and Classification of Patients Into GOLD Stages

BACKGROUND: The COPD Assessment Test (CAT) was developed as a simple instrument to assess health status in patients with COPD. This study aimed to systematically review the determinants of the CAT score, its ability to predict clinical outcomes, and the agreement between CAT (>= 10) and the modified Medical Research Council scale (mMRC >= 2) to categorize patients into the new Global Initiative for Chronic Obstructive Lung Disease classification system. METHODS: From January 1, 2009, to June 30, 2015, databases were searched for studies using CAT in adults with COPD and in general populations aiming to detect COPD. Two investigators independently screened, selected, and extracted data by using a standardized form. Where appropriate, the results were combined in a random effects meta-analysis. RESULTS: Of 453 studies, 17 were included, and eight were used in the meta-analysis. The models to predict the CAT score were able to explain < 50% of its variance. CAT scores can indicate risk of exacerbation, depression, acute deterioration in health status, and mortality. All studies found a different proportion of patients in each Global Initiative for Chronic Obstructive Lung Disease category using CAT >= 10 or mMRC >= 2. On average, the distribution was 13% different according to the instrument used. The k agreement between CAT and mMRC ranged from 0.13 to 0.77. CONCLUSIONS: CAT may be used as a complementary tool in a patient's clinical assessment to predict COPD exacerbation, health status deterioration, depression, and mortality. The interpretation of this meta-analysis does not support the use of the recommended cutoff points of >= 10 for CAT and >= 2 for mMRC as equivalents for the purpose of assessing patient symptoms.