CAT (COPD ASSESSMENT TEST) In Bronchiectasis: Minimum Clinically Important Difference and Psychometric Validation. A Prospective Study.

Abstract

BACKGROUND:

Health-related Quality of Life (QoL) is one of the most important endpoints in bronchiectasis (BE). However, the majority of HRQoL questionnaires are time-consuming or not validated in BE. The COPD Assessment Test (CAT) in an easy-to-use questionnaire. The objective of this study was to perform a complete validation of CAT in BE.

METHODS:

Observational, multicenter, prospective study in BE patients. Psychometric properties of CAT were measured: internal consistency (Cronbach´s α), repeatability (test-retest; intra-class correlation coefficient [ICC]), discriminant validity (correlation with severity scores), convergent validity (correlation with some validated QoL questionnaire and other clinical variables of interest), longitudinal validity (measuring before and after each exacerbation during follow-up to determine the sensitivity to change and responsiveness), predictive validity to future exacerbations, and finally minimum clinically important difference (MCID).

RESULTS:

96 patients were included and followed up for 1 year. Mean age was 62.2 (15.6) years (79.2% women). CAT showed an excellent internal consistency (α: 0.95) and repeatability (ICC: 0.95). The validity of CAT was excellent in all the measures (almost all with a Pearson coefficient >0.40) except for the correlations with the severity scores (Pearson coefficient between 0.22-0.26). Sensitivity to change before and after exacerbations was set at between 5.4 and 5.8 points. A CAT value ≥10 points showed a prognostic value of patients with more than 1 exacerbation, and finally the MCID was set at 3 points.

CONCLUSIONS:

The CAT presented excellent psychometric properties and is a questionnaire that is easy to use and interpret in patients with BE.