0
Correspondence |

Responsiveness of the COPD Assessment TestResponsiveness of the COPD Assessment Test: The Minimal Clinically Important Difference Does Matter FREE TO VIEW

Janwillem W. H. Kocks, MD, PhD; Ioanna G. Tsiligianni, MD, PhD; Thys van der Molen, MD, PhD
Author and Funding Information

From the Department of General Practice and Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen.

Correspondence to: Janwillem W. H. Kocks, MD, PhD, Department of General Practice, University Medical Center Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands; e-mail: j.w.h.kocks@umcg.nl

Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr van der Molen received grants from AstraZeneca, GlaxoSmithKline, and Merck Sharp & Dohme Corp; received advisory board honoraria from GlaxoSmithKline, Merck Sharp & Dohme Corp, AstraZeneca, and Nycomed GmbH; and is the copyright holder of the Clinical COPD Questionnaire. Drs Kocks and Tsiligianni have reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.


Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr van der Molen received grants from AstraZeneca, GlaxoSmithKline, and Merck Sharp & Dohme Corp; received advisory board honoraria from GlaxoSmithKline, Merck Sharp & Dohme Corp, AstraZeneca, and Nycomed GmbH; and is the copyright holder of the Clinical COPD Questionnaire. Drs Kocks and Tsiligianni have reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2012;142(1):267-268. doi:10.1378/chest.12-0462
Text Size: A A A
Published online

To the Editor:

With the inclusion of symptoms/health status in the most recent GOLD (Global Initiative for Chronic Obstructive Lung Disease) guidelines,1 a large step has been made to involve the patient’s view of the burden of disease in decision making. We welcome this development but wonder why the GOLD committee chose the COPD Assessment Test (CAT) by GlaxoSmithKline.

Clinicians and researchers need information on how to interpret scores, and the study by Jones et al2 in this issue of CHEST (see page 134) provides important information about this topic. However, we would like to raise two issues. First, how much change in scores would one expect after exacerbations and pulmonary rehabilitation? Second, what would be the minimal clinically important difference (MCID) of the CAT based on this study?

Jones et al2 describe the CAT score changes during an exacerbation and after rehabilitation. Exacerbation recovery resulted in a mean CAT score improvement of −1.4 points in all 67 patients and −2.6 points in clinician-defined responders. Are these clinically relevant changes in scores? We would suppose so considering the clinicians’ judgment. However, to enable good interpretation of the −2.6-point change, the CAT MCID should be known.

Jones et al2 would allow proper calculations of the MCID by both distribution and anchor-based methods. Based on their study, the CAT MCID can be estimated using one of the distribution-based methods: the SEM.3 The MCID would be 1.96×7.7×√1−0.8=6.75 points in this study. In a study of 90 Greek patients, the 1.96 SEM was 4.84, 3.76, and 0.41 for the St. George Respiratory Questionnaire, CAT, and Clinical COPD Questionnaire (CCQ), respectively,4 which is similar to previously published MCIDs for the St. George Respiratory Questionnaire and CCQ.3,5 The reported changes in responders (−2.6 points) will not reach this MCID by far, suggesting limited responsiveness of the CAT to exacerbation recovery.

In the second study described by Jones et al,2 the effects of pulmonary rehabilitation (one of the most effective treatments for patients with COPD) is −2.2 points, which is also disappointingly low when considering the MCID calculated from the exacerbations study. The disappointing sensitivity for change is also confirmed by a study by Dodd et al,6 who showed that the effect size of the Chronic Respiratory Questionnaire is −0.8, whereas the effect sizes of the CCQ and CAT are 0.6 and 0.4, respectively. We, therefore, challenge the conclusion that the CAT is sensitive to change and would ask the authors to calculate the MCID on the data from the presented study and reconsider their conclusion.

GOLD CommitteeGOLD Committee. Global strategy for the diagnosis, management and prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Initiative for Chronic Obstructive Lung Disease website.http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.html. Updated December 2011. Accessed February 20, 2012.
 
Jones PW, Harding G, Wiklund I, et al. Tests of the responsiveness of the COPD Assessment Test following acute exacerbation and pulmonary rehabilitation. Chest. 2012;142(1):134-140. [PubMed] [CrossRef]
 
Kocks JWH, Tuinenga MG, Uil SM, van den Berg JWK, Ståhl E, van der Molen T. Health status measurement in COPD: the minimal clinically important difference of the clinical COPD questionnaire. Respir Res. 2006;7:62.
 
Tsiligianni IG, van der Molen T, Moraitaki D, et al. Assessing health status in COPD. A head-to-head comparison between the COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ) [published online ahead of print May 20, 2012]. BMC Pulm Med. In press. doi:10.1186/1471-2466-12-20.
 
Jones PW. St. George’s Respiratory Questionnaire: MCID. COPD. 2005;2(1):75-79.
 
Dodd JW, Hogg L, Nolan J, et al. The COPD assessment test (CAT): response to pulmonary rehabilitation. A multicentre, prospective study. Thorax. 2011;66(5):425-429.
 

Figures

Tables

References

GOLD CommitteeGOLD Committee. Global strategy for the diagnosis, management and prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Initiative for Chronic Obstructive Lung Disease website.http://www.goldcopd.org/guidelines-global-strategy-for-diagnosis-management.html. Updated December 2011. Accessed February 20, 2012.
 
Jones PW, Harding G, Wiklund I, et al. Tests of the responsiveness of the COPD Assessment Test following acute exacerbation and pulmonary rehabilitation. Chest. 2012;142(1):134-140. [PubMed] [CrossRef]
 
Kocks JWH, Tuinenga MG, Uil SM, van den Berg JWK, Ståhl E, van der Molen T. Health status measurement in COPD: the minimal clinically important difference of the clinical COPD questionnaire. Respir Res. 2006;7:62.
 
Tsiligianni IG, van der Molen T, Moraitaki D, et al. Assessing health status in COPD. A head-to-head comparison between the COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ) [published online ahead of print May 20, 2012]. BMC Pulm Med. In press. doi:10.1186/1471-2466-12-20.
 
Jones PW. St. George’s Respiratory Questionnaire: MCID. COPD. 2005;2(1):75-79.
 
Dodd JW, Hogg L, Nolan J, et al. The COPD assessment test (CAT): response to pulmonary rehabilitation. A multicentre, prospective study. Thorax. 2011;66(5):425-429.
 
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543