Validation of the COPD Assessment Test (CAT) as an outcome measure in bronchiectasis

Abstract Introduction Objective assessment of symptoms in bronchiectasis is important for research and in clinical practice. The COPD Assessment Test (CAT) is a short, simple assessment tool widely used in chronic obstructive pulmonary disease (COPD). The items included in the CAT are not specific to COPD and also reflect the dominant symptoms of bronchiectasis. We therefore performed a study to validate the CAT as an outcome measure in bronchiectasis. Methods The CAT was administered to two cohorts of bronchiectasis patients along with other quality of life questionnaires. Patients underwent comprehensive clinical assessment. One cohort had repeated questionnaires collected before-and-after treatment of acute exacerbations. We analysed convergent validity, repeatability and responsiveness of the score and calculated the minimum clinically important difference (MCID) using a combination of distribution and anchor based methods. Results In both cohorts there were positive correlations between the CAT and the St.George’s Respiratory Questionnaire (SGRQ) (r=0.90,p Discussion CAT is a valid, responsive symptom assessment tool in bronchiectasis. The MCID is estimated as 4 points.