Abstract
The COPD assessment test (CAT) is a self-administered questionnaire that measures health-related quality of life. We aimed to systematically evaluate the literature for reliability, validity, responsiveness and minimum clinically important difference (MCID) of the CAT.
Multiple databases were searched for studies analysing the psychometric properties of the CAT in adults with chronic obstructive pulmonary disease. Two reviewers independently screened, selected and extracted data, and assessed methodological quality of relevant studies using the COSMIN checklist.
From 792 records identified, 36 studies were included. The number of participants ranged from 45 to 6469, mean age from 56 to 73 years, and mean forced expiratory volume in 1 s from 39% to 98% predicted. Internal consistency (reliability) was 0.85–0.98, and test–retest reliability was 0.80–0.96. Convergent and longitudinal validity using Pearson’s correlation coefficient were: SGRQ-C 0.69–0.82 and 0.63, CCQ 0.68–0.78 and 0.60, and mMRC 0.29–0.61 and 0.20, respectively. Scores differed with GOLD stages, exacerbation and mMRC grades. Mean scores decreased with pulmonary rehabilitation (2.2–3 units) and increased at exacerbation onset (4.7 units). Only one study with adequate methodology reported an MCID of 2 units and 3.3–3.8 units using the anchor-based approach and distribution-based approach, respectively. Most studies had fair methodological quality.
We conclude that the studies support the reliability and validity of the CAT and that the tool is responsive to interventions, although the MCID remains debatable.
Abstract
Studies support the reliability, validity and responsiveness of the CAT as a HRQoL tool but its MCID remains unclear http://ow.ly/xkVNA
Footnotes
For editorial comments see page 833.
This article has supplementary material available from erj.ersjournals.com
Support statement: This research was supported by a studentship award from the Research Institute of the McGill University Health Centre (Graduate Student Scholarship award to Nisha Gupta), the Collaborative Innovative Research Fund (CIRF) GSK Canada, the Canadian Cohort Obstructive Lung Disease (CanCOLD) Canadian Institutes of Health Research (CIHR)/Rx&D Collaborative Research Program (IRO-93326), and the Respiratory Health Network of the Fonds de recherche du Québec – Santé (FRQS).
Conflict of interest: Disclosures can be found alongside the online version of this article at erj.ersjournals.com
- Received February 5, 2014.
- Accepted May 22, 2014.
- ©ERS 2014