Chest
Volume 150, Issue 5, November 2016, Pages 1069-1079
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Original Research: COPD
The COPD Assessment Test: Can It Discriminate Across COPD Subpopulations?

https://doi.org/10.1016/j.chest.2016.06.016Get rights and content

Background

The COPD Assessment Test (CAT) is a valid disease-specific questionnaire measuring health status. However, knowledge concerning its use regarding patient and disease characteristics remains limited. Our main objective was to assess the degree to which the CAT score varies and can discriminate between specific patient population groups.

Methods

The Canadian Cohort Obstructive Lung Disease (CanCOLD) is a random-sampled, population-based, multicenter, prospective cohort that includes subjects with COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] classifications 1 to 3). The CAT questionnaire was administered at three visits (baseline, 1.5 years, and 3 years). The CAT total score was determined for sex, age groups, smoking status, GOLD classification, exacerbations, and comorbidities.

Results

A total of 716 subjects with COPD were included in the analysis. The majority of subjects (72.5%) were not previously diagnosed with COPD. The mean FEV1/FVC ratio was 61.1 ± 8.1%, with a mean FEV1 % predicted of 82.3 ± 19.3%. The mean CAT scores were 5.8 ± 5.0, 9.6 ± 6.7, and 16.1 ± 10.0 for GOLD 1, 2, and 3+ classifications, respectively. Higher CAT scores were observed in women, current smokers, ever-smokers, and subjects with a previous diagnosis of COPD. The CAT was also able to distinguish between subjects who experience exacerbations vs those who had no exacerbation.

Conclusions

These results suggest that the CAT, originally designed for use in clinically symptomatic patients with COPD, can also be used in individuals with mild airflow obstruction and newly diagnosed COPD. In addition, the CAT was able to discriminate between sexes and subjects who experience frequent and infrequent exacerbations.

Trial Registry

ClinicalTrials.gov; No.: NCT00920348; Study ID No.: IRO-93326.

Section snippets

Study Population, Design, and Assessments

Canadian Cohort Obstructive Lung Disease (CanCOLD) is a prospective cohort study designed to track > 1,500 subjects (male and female subjects aged ≥ 40 years) recruited by using a random sampling frame from nine urban and suburban areas in Canada and based on the International Burden of Obstructive Lung Disease Initiative.6, 7 The cohort comprises two balanced COPD subpopulations (GOLD 1 and GOLD ≥ 2) and two age- and sex-matched non-COPD subjects (ever-smoker for those at risk and never smoker

Demographic and Subject Characteristics

A total of 716 subjects with COPD who completed the baseline visit in the CanCOLD study were included in this analysis. Table 1 summarizes the participants’ sociodemographic and clinical characteristics. Forty percent of subjects were women, and approximately one-quarter of the individuals were < 60 years of age and in the group aged ≥ 75 years. More than one-half of the study population was classified as having mild airflow obstruction (GOLD 1). Almost three-quarters of the subjects had not

Discussion

In the present observational study, we confirmed that the CAT is valid according to specific characteristics in a random-sampled, population-based cohort of individuals with COPD. We tested the CAT in individuals with undiagnosed COPD and in those with mild disease and found that CAT scores are increased (ie, a worsened health status) in subjects with worsening airflow obstruction and in those with exacerbations. Similar to symptom scores and reports in other medical and respiratory diseases,

Conclusions

The present study provides cross-sectional and longitudinal data on the CAT from a well-characterized, population-based sample of subjects with COPD. Our characterization of CAT scores according to women, those with mild airflow obstruction vs moderate/severe obstruction, and those with exacerbations beyond GOLD classification established that the questionnaire is a valid measurement tool to assess health status in a population-based cohort that reflects COPD patients at large. These results

Acknowledgments

Author contributions: J. B. takes responsibility for the content of the manuscript, including the data and analysis. N. G. and J. B. contributed to the conception and implementation of the study, acquisition and analysis of the data, and writing and revision of the manuscript. L. P., A. B., W. C. T., S. D. A., K. R. C., J. M. F., P. H., D. D. M., F. M., D. E. O., B. L. W., and D. S. contributed to the acquisition of the data and the revision of the article. P. Z. L. contributed to the analysis

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FUNDING/SUPPORT: The Canadian Cohort Obstructive Lung Disease (CanCOLD) study is currently funded by the Canadian Respiratory Research Network; industry partners are AstraZeneca Canada Ltd., Boehringer Ingelheim Canada Ltd., GlaxoSmithKline Canada Ltd., and Novartis. Researchers at RI-MUHC Montreal and Icapture Centre Vancouver lead the project. Previous funding partners were the CIHR (CIHR/Rx&D Collaborative Research Program Operating Grants, 93326) and the Respiratory Health Network of the FRSQ; industry partners were Almirall, Merck, Nycomed, Pfizer Canada Ltd., and Theratechnologies.

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