The Relationship between COPD Assessment Test (CAT) Scores and Severity of Airflow Obstruction in Stable COPD Patients

BACKGROUND COPD is a major cause of morbidity in smokers. The COPD assessment test (CAT) is a validated test for evaluation of COPD impact on health status. CAT is not a diagnostic test and pulmonary function test (PFT) still remains the most important diagnostic test. However, its predictive value for evaluation of disease impact is weak. The purpose of this study was to determine the relationship between CAT score and PFT in COPD patients. MATERIALS AND METHODS We evaluated 105 patients with stable COPD. Demographic data were obtained at baseline. Severity of airflow obstruction was assessed by standard spirometry and classified by the Global initiative for Obstructive Lung Disease (GOLD) criteria. Then, the impact of COPD on health status was assessed using CAT. The CAT scores were categorized into four groups. We statistically compared the relationship between CAT score, COPD stages, CAT groups and PFT. RESULTS The mean age of patients and mean period of smoking (p/y) were 59.60±11.93SD and 35.43±15.33 SD yrs, respectively. The mean FEV1%predicted was 71.01±26.70SD. The mean CAT score was 19.61±8.07 SD. The correlation between the severity of smoking and GOLD classification was significant (p=0.006). There was a significant association between the FEV1%predicted and total CAT score (r= -0.55, p< 0.001). The correlation between mean FEV1%predicted and mean score of CAT groups 1, 2, 3, and 4 was statistically significant (p<0.001). CONCLUSION The relationship between CAT score and FEV1%predicted suggests that CAT is linked to severity of airflow limitation and GOLD classification in stable COPD patients. Health status as measured by CAT worsens with severity of airflow limitation.