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Original Research: Copd |

Validity of the COPD Assessment Test Translated Into Local Languages for Asian PatientsAsian Validation Studies of COPD Assessment Test FREE TO VIEW

Namhee Kwon, MD, PhD; Muhammad Amin, DrMed; David S. Hui, MD, FCCP; Ki-Suck Jung, MD, PhD; Seong Yong Lim, MD, PhD; Huu Duy Ta, MD; Thi Thuy Linh Thai, MD; Paul W. Jones, PhD
Author and Funding Information

From GlaxoSmithKline (Dr Kwon), Singapore, Republic of Singapore; the Faculty of Medicine (Dr Amin), Airlangga University, Surabaya, Indonesia; the Department of Medicine and Therapeutics (Dr Hui), The Chinese University of Hong Kong, Hong Kong; the Division of Pulmonary, Allergy, and Critical Care Medicine (Dr Jung), Hallym University Medical College, Seoul, South Korea; the Division of Pulmonary and Critical Care Medicine (Dr Lim), Department of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, South Korea; the Bach Mai Hospital (Dr Ta), Hanoi, Vietnam; the Trieu An Hospital (Dr Thai), Ho Chi Minh City, Vietnam; the Department of Pulmonology and Respiratory Medicine (Dr Yunus), University of Indonesia, Jakarta, Indonesia; and the Division of Clinical Science (Dr Jones), St. George’s University, London, England.

Correspondence to: Namhee Kwon, MD, PhD, GlaxoSmithKline, 150 Beach Rd, #22-00 Gateway West, Singapore 189720, Republic of Singapore; e-mail: namhee.n.kwon@gsk.com


Funding/Support: This study was funded by GlaxoSmithKline [GSK Study Number: SAM115264].

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


Chest. 2013;143(3):703-710. doi:10.1378/chest.12-0535
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Objective:  Our objective was to evaluate the validity of the COPD Assessment Test (CAT), translated locally, for measuring the health status of patients in Asian countries.

Methods:  A pooled analysis of cross-sectional studies from Indonesia, Korea, Vietnam, and Hong Kong was performed. Smokers or ex-smokers, aged ≥ 40 years, with a smoking history of ≥ 10 pack-years and a COPD diagnosis in the past 6 months or more were recruited. Demographic, smoking, and COPD history and spirometry data were collected from patients who completed the CAT or St. George’s Respiratory Questionnaire (SGRQ) and had their dyspnea assessed.

Results:  The study included 333 patients with mean age of 69 ± 9 years and smoking history of 38 ± 25 pack-years; 82% had ceased smoking. One-third suffered from cardiovascular comorbidities, 72% reported at least one exacerbation in the past year, and 82% recorded at least moderate health impairment (CAT scores ≥ 10 units). The CAT score was positively correlated with the SGRQ score (r = 0.72, P < .001) and Medical Research Council (MRC) dyspnea score (r = 0.50, P < .001) and poorly correlated with the FEV1 (r = −0.23, P < .001) and number of exacerbations in the past year (r = 0.11, P = .04). The relationships between the CAT score and SGRQ score, MRC dyspnea score, or FEV1 did not differ between countries (P value for interaction term = 0.76, 0.75, and 0.06, respectively).

Conclusions:  The CAT correlated well with the SGRQ and MRC dyspnea score in all countries, and the relationship did not differ between countries despite varying patient characteristics. This suggests that a CAT score in one of these countries has the same clinical significance as the same score in another.

Figures in this Article

COPD, a common, preventable, and treatable disease, is characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases.1 Cigarette smoking is a known risk factor for the development and progression of COPD.2 In addition, exposure to secondhand smoke and fumes from the burning of biomass fuel commonly used for cooking has significant health impact on nonsmokers.3,4

COPD is one of the fastest growing causes of death; from its sixth position in 2000, it is expected to climb to the third position within a period of 20 years (2020). In 2004, COPD accounted for 5.1% of all deaths and afflicted 63.6 million people worldwide. More than one-half of the sufferers were in the Asia-Pacific region, where COPD prevalence is estimated at 10.6% of the adult population.57 This can be attributed to the high rates of smoking, especially among men, in countries such as China, Japan, South Korea, and Taiwan.7 In addition, a low level of COPD awareness not only by health-care providers but also by the patients themselves4 has resulted in undertreatment of the disease. Prompt interventions, including smoking cessation, and improvement in awareness of the disease are crucial to reduce burden of the disease.

Health status measurement is now a routine part of clinical research studies, but instruments such as the St. George’s Respiratory Questionnaire (SGRQ)8 and Chronic Respiratory Questionnaire, although comprehensive, are lengthy and time consuming.9,10 The COPD Assessment Test (CAT11), a new eight-item self-administered disease-specific questionnaire, has been recommended for the assessment of COPD disease severity under the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2011 document.1 It was developed with significant patient input and contained core items with good measurement properties. Using a six-point semantic differential scale, it is easy for patients to complete and has been shown to be a reliable measure of the overall COPD impact on their health status.12 The CAT was developed and validated in the United States and Europe.13,14 However, there were limited validation studies in Asia. This study evaluates the correlation between the CAT and SGRQ using a pooled analysis of local studies carried out in four Asian countries.

Three Asian countries (Indonesia, Korea, and Vietnam) and Hong Kong independently conducted local cross-sectional studies designed to evaluate the validity of the CAT. Each study was conducted in accordance with Good Clinical Practice as outlined in the Declaration of Helsinki 2000. All necessary approvals for the trials and centers in each study were obtained from their respective institutional review boards. (See e-Appendix 1 for the list of institutional review board approvals.) The four countries agreed to provide patient-level data to perform the pooled analysis described here.

Study Population

Patients were recruited from seven university-affiliated hospitals, two secondary hospitals, and four primary care clinics between November 2010 and June 2011. They were outpatients ≥ 40 years of age who were smokers or ex-smokers with a smoking history of ≥ 10 pack-years and had a diagnosis of COPD in the past 6 months or more. Those with an active respiratory disorder other than COPD or a current diagnosis of asthma or who were unable to complete the questionnaires were excluded. Written informed consent was obtained from each patient prior to his or her participation in the study.

Study Design

A cross-sectional study was conducted using a common case report form to ensure that data collection across countries was consistent. Patient characteristics included demographic information, smoking and COPD history, medication history, and comorbidities (includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure [any causes], and ischemic heart disease, or on antihypertensive and other cardiovascular drugs). During the same visit, the patient’s breathlessness was assessed using the Medical Research Council (MRC) dyspnea scale. A spirometry test was performed if there were no prior documented results within 6 months of the study visit. Lung function variables were calculated using the locally derived spirometry reference equations for Hong Kong,15 Indonesia,16 and Korea.17 The National Health and Nutrition Examination Survey III18 equations with correction factors for Asians were used for Vietnam.19

Questionnaires

Patients were asked to complete the SGRQ and CAT questionnaires during the study visit. (See e-Appendix 2 for the SGRQ linguistic translation certificate and written permissions for the use of the SGRQ in the country studies.) Validated translations of the standard SGRQ questionnaire with three domains for symptoms (eight items), activity (16 items) and impacts (26 items) were used. The SGRQ has a score range of 0 to 100. The CAT questionnaire had eight items, covering cough, phlegm, chest tightness, breathlessness, activity limitation, confidence, sleep, and energy. It was translated into the local language of the country (Traditional Chinese, Indonesian, Korean, or Vietnamese) in accordance with the International Society for Pharmacoeconomics and Outcome Research translation and cultural adaptation process for patient-reported outcomes.20

Statistical Methods

Demographic data and other baseline characteristics, including CAT, MRC, and SGRQ scores and postbronchodilator FEV1 % predicted values, were presented using descriptive statistics. Disease severity was assessed using the GOLD severity classification1 based on the subject’s postbronchodilator FEV1 % predicted value.

The difference between CAT scores across comorbidities groups and exacerbation history was assessed using one-way analysis of variance and adjusted for age, sex, BMI, FEV1 % predicted, and country in a general linear model analysis with Bonferroni adjustments for multiple comparisons. Statistical significance was set at P < .05. Associations between the CAT and SGRQ, MRC, and FEV1 % predicted were tested using Pearson or Spearman correlations upon normality assumptions. Comparison of the relationship between CAT and the reference measure across countries was tested using analysis of covariance (ANCOVA). All the statistical analyses were performed by using the SPSS Statistics version 18 (IBM).

Patient Characteristics

The study population consisted of 333 patients who had completed the CAT questionnaire. Of these, four did not complete the SGRQ questionnaire. There were 101 patients from Indonesia, 100 each from Korea and Vietnam, and 32 from Hong Kong. The demographic and clinical characteristics of these patients are summarized in Table 1. The mean age of the patients was 69.3 ± 9.4 years, and 97.6% of them were men. The mean duration of COPD disease from diagnosis was approximately 4 years. The patients had a mean smoking history of 37.8 ± 25.2 pack-years, and most (82.3%) had ceased smoking. Approximately one-third of patients suffered from at least one cardiovascular comorbidity, and 13.8% had ischemic heart disease or heart failure.

Table Graphic Jump Location
Table 1 —Demographic and Clinical Characteristics

Data are given as No. (%) unless otherwise indicated. GOLD = Global Initiative for Chronic Obstructive Lung Disease.

a 

GOLD severity classification based on the subject’s postbronchodilator FEV1 % predicted value.

b 

Includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure (any causes), ischemic heart disease, on antihypertensive drugs, on other cardiovascular drugs.

c 

Includes heart failure (any causes), ischemic heart disease, on antihypertensive drugs, on other cardiovascular drugs.

Approximately one-half of the patients (52.2%) were classified as GOLD grade I or II. There were some differences at the country level: 75% of the Korean patients classified as GOLD grade I or II, but only 48.5% and 39.0% of Indonesian and Vietnamese patients, respectively. Seventy-two percent of the patients reported at least one exacerbation in the past year. There was no observable pattern between GOLD grades and the number of exacerbations in the past year: 66.5% of the grade II patients had at least one exacerbation in the past year compared with 75% of grade III and 74.3% of grade IV patients. Sixty-four percent of patients were treated with antibiotics and 56% with systemic corticosteroids in the previous year.

Theophyllines were the most commonly prescribed treatment (70.0% of the patients), followed by inhaled short-acting β2-agonists (49.5%). About 26.1% of the patients had a flu vaccination in the past year. There were some differences in the treatments between the participating countries. Theophyllines were used to treat a greater percentage of the Indonesian and Vietnamese patients (78.2%-80.0%) compared with Hong Kong patients (43.8%), and more Vietnamese patients (79.0%) were given antibiotics compared with Koreans (44.0%). A combination of inhaled corticosteroids and long-acting β2-agonists was used in 60.0% of Korean patients compared with 29.7% of Indonesian patients, and 71.0% of Korean had flu vaccinations, whereas no Indonesian was reported as having been vaccinated.

CAT Scores

The mean CAT score for the study population was 17.7 ± 8.2, with a median of 18 (range, 0-35). Eighty-two percent of the patients with COPD had a CAT score≥ 10 units. Figure 121 shows the mean CAT scores by subgroup for BMI, disease severity (using the GOLD grades), number of comorbidities, and country. The mean scores between the subgroups of these patient characteristics were significantly different, whereas those between subgroups of age (≤ 65 years and > 65 years), smoking status (current smoker and ex-smoker), and sex (male and female) were not.

Figure Jump LinkFigure 1. CAT scores by subgroups for characteristics for which the difference in mean scores between subgroups were significant. A, Mean CAT scores for BMI (kg/m2) < 18.5, ≥ 18.5, < 23.0, and ≥ 23.021 were 19.1, 18.7, and 15.2, respectively; P = .001. B, Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity classification based on the subject’s postbronchodilator FEV1 % predicted value: mean CAT scores for GOLD grade I, II, III, and IV were 16.5, 16.0, 19.0, and 21.3, respectively; P = .001. C, Mean CAT scores for 0, 1-2, ≥ 3 comorbidities (includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure [any cause], ischemic heart disease, on antihypertensive drugs, and on other cardiovascular drugs) were 17.7, 16.6, and 20.6, respectively; P = .054. D, Mean CAT scores for Hong Kong, Korea, Indonesia, and Vietnam were 13.9, 16.9, 18.1, and 19.3, respectively; P = .008. All mean scores were unadjusted for confounders. CAT = COPD Assessment Test.Grahic Jump Location

The unadjusted differences in CAT scores between patients grouped by comorbidity (none, one or two, and three or more) were not significant (P = .054); however, the differences were significant after adjusting for BMI, sex, disease severity, and country (P = .004). There was no observed difference in the CAT scores for patients with cardiovascular comorbidities compared with those who had none before and after adjusting for the covariates (Table 2), but when cardiovascular comorbidity was restricted to ischemic heart disease and heart failure there was a significant difference (CAT score for patients with cardiac comorbidity, 20.4 vs 17.3 for those without; P = .014).

Table Graphic Jump Location
Table 2 —CAT Score and Measures of Impairment

CAT = COPD Assessment Test. See Table 1 legend for expansion of other abbreviation.

a 

The P value shows the test of significance between the mean CAT value of the classes of the characteristic using the one-way analysis of variance method.

b 

The P value is adjusted for age, BMI, sex, disease severity (GOLD severity classification based on the subject’s postbronchodilator FEV1 % predicted value), and country in a general linear model analysis with Bonferroni adjustments for multiple comparisons.

c 

Includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure (any causes), ischemic heart disease, on antihypertensive drugs, and on other cardiovascular drugs.

d 

Includes heart failure (any causes), ischemic heart disease, on antihypertensive drugs, and on other cardiovascular drugs.

Correlation Between CAT and SGRQ Score

The CAT score was positively correlated with the SGRQ total score (r = 0.72, P < .001) and its three component domains: Activity, Symptoms, and Impacts (r = 0.58, 0.61, and 0.68, respectively; all P < .001) (Fig 2). The mean CAT score increased by 3.2 units for each 10-unit increase in SGRQ total score. The correlation coefficients between CAT and the SGRQ total score were similar in the individual countries, ranging from 0.68 for Vietnam to 0.77 for Korea (all P < .001). The relationship between the CAT and the SGRQ score did not differ significantly between countries (P = .76 for ANCOVA interaction term to test for a difference in the slopes of the CAT vs SGRQ relationship in different countries) (Fig 3).

Figure Jump LinkFigure 2. A, Scatterplot of CAT scores and SGRQ Total scores. B, Scatter plot of CAT scores and SGRQ Activity scores. C, Scatter plot of CAT scores and SGRQ Symptoms scores. D, Scatter plot of CAT scores and SGRQ Impacts scores. SGRQ = St. George’s Respiratory Questionnaire. See Figure 1 legend for expansion of other abbreviation.Grahic Jump Location
Figure Jump LinkFigure 3. Scatterplot of CAT score to SGRQ total score by country with a regression line for each country. The slopes of regression lines are not significantly different by country (P = .759, interaction term for difference in the slopes when tested using ANCOVA analysis controlled for the country covariate). ANCOVA = analysis of covariance. See Figure 1 and 2 legends for expansion of other abbreviations.Grahic Jump Location
Correlation Between CAT Score and Other Measures of Disease Severity

There was a positive correlation between CAT score and MRC dyspnea score (r = 0.50, P < .001) and a weak correlation between CAT score and FEV1 % predicted (r = −0.23, P < .001). The relationship of the CAT with MRC dyspnea score and FEV1 % predicted did not differ between countries (P value for the interaction term, 0.75 and 0.063, respectively).

The correlation between the mean CAT score and number of exacerbations in the past year was low (r = 0.11, P = .04), although the score increased from 16.6 to 18.9 as the number of exacerbations increased from none to two or more (Table 2). Differences in unadjusted mean score between the exacerbation subgroups were not significant (P = .096) and after adjusting for the other covariates (P = .102).

This pooled analysis of cross-sectional studies from four Asian countries showed that the CAT behaved in a very similar manner, in terms of its relationship to SGRQ score and MRC dyspnea scores, to that reported in Western countries.13,22 It also adds new information about the relationship between CAT and the three domains of the SGRQ, which address COPD symptoms, disturbance of physical activity, and psychosocial impact of the disease. This supports findings obtained in US patients, which showed that the CAT correlated with each of the four domains of the Chronic Respiratory Questionnaire, namely dyspnea, fatigue, emotional function, and mastery (the patient’s feeling of control over the disease).23 These studies therefore provide complementary evidence that the CAT addresses a wide range of effects of COPD on the patient’s health status. When compared with a recently published European study,14 the patient profiles were similar in terms of age (mean, 64.9 years vs 69.3 years in our study), smoking history (mean, 40.4 vs 37.8 pack-years), FEV1 % predicted (mean, 56.7% vs 52.1%) and MRC dyspnea score (mean, 2.5 vs 2.8). Asian patients, however, had a shorter reported duration of COPD (mean, 4.0 years vs 9.4 years for Europeans), and one-half of them were in grade I or II, probably because of a lower awareness of the disease. There was a high rate of exacerbations in patients with moderate-grade airflow limitation (GOLD grade II). About two-thirds of these patients had at least one exacerbation in the last year. This is supported by data showing the high use of systemic corticosteroids and antibiotics; these drugs were less used in the European study: corticosteroids (56.2% vs 34.8%) and antibiotics (64.0% vs 55.3%).

Health status in these patients with COPD was significantly impaired at all levels of airflow limitation. Based on the CAT score of ≥ 10 units24 as proposed in the GOLD 2011 document,1 most (82%) of the patients with COPD were experiencing poor quality of life. The correlation between CAT score and FEV1 % predicted was low and very similar to that reported in another study.13 This showed that there was considerable heterogeneity in health-related quality of life impairment among patients within each GOLD grade group. Even in patients with mild airway obstruction (GOLD grade I), the CAT score of 16.5 units was high but consistent with the score of 16.2 in GOLD grade I patients in Europe.13

Our study showed that the CAT performed consistently in all countries despite having different patient characteristics. This conclusion is supported by the nonsignificant difference in slope between CAT score and SGRQ, and MRC dyspnea scores, and FEV1 % predicted between the countries. This is encouraging and suggests that CAT scores have the same clinical meaning in different groups of patients in different countries. It also suggests that if a correct linguistic and cultural validation is performed, there may not be a need to evaluate the validity of the CAT with SGRQ or other measurers prior to its use.

There was no correlation between CAT score and the number of exacerbations experienced in the previous year. A limitation of our study is that we did not specifically define the nature of an exacerbation, and the data were based on the patient’s recollection. Despite that, the proportions of the patients who received corticosteroids and antibiotics (56.2% and 64.0%, respectively), typical treatments for exacerbations, were similar to the proportion of patients who had at least one exacerbation in the past year (71.8%), which provides some support that the reported exacerbation rate was reliable. The CAT scores were not significantly different between patients with zero and one or more cardiovascular comorbidities, unlike other studies,25,26 but when cardiovascular comorbidity was restricted to only ischemic heart disease and heart failure, there was a significant difference. We have limited our study to comorbidities with underlying inflammation. This choice, along with the small number of female subjects and countries in our study, may have limited the generalization of our findings to the general population.

Our study has shown that the CAT is capable of capturing the wide impact of COPD on the patient’s health status despite its simplicity. The consistent finding in correlations between the CAT score and SGRQ score, MRC dyspnea score, or FEV1 % predicted across the four countries with different patient characteristics showed that the CAT is reliable at the patient level. It appears to be as valid in these Asian countries as in Europe and the United States and enables sophisticated measurement of health status in a clinic setting. Its size and ease of scoring permit its use in routine practice27 and should deliver one of its design targets, to provide an effective physician-patient communication tool for COPD disease management.11

Author contributions: Dr Kwon had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Kwon: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Amin: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Hui: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Jung: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Lim: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Ta: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Thai: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Yunus: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Dr Jones: contributed to conceptualizing the study design, drafting the article or revising it critically for important intellectual content, and approving the final version to be submitted for publication.

Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr Namhee Kwon is an employee of GlaxoSmithKline. Dr Thai received other grant monies from the Ho Chi Min City Respiratory Society. Dr Jones received university grant funding, consulting fees, and speaker’s honoraria from GlaxoSmithKline. Drs Amin, Hui, Jung, Lim, Ta, and Yunus have reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Role of sponsors: GlaxoSmithKline owns the copyrights of the COPD Assessment Test (CAT) questionnaire used in the present study. GlaxoSmithKline has conducted the translation of the CAT questionnaire into the languages and approved the use of the CAT for the validation studies.

Other contributions: We thank Amira Permatasari Tarigan, MD; Susanthy Djajalaksana, MD; Guihyun Nam, MD; Young Mok Lee, MD; Bong Chun Lee, MD; and Jae Myung Lee, MD, for their contributions to the individual studies (see e-Appendix 3 for list of participating sites). Statistical analyses were performed by Yiong-Huak Chan, PhD (Mathematics), and medical writing support was provided by Sen-Kwan Tay, MSc (Bioinformatics), of Research2Trials Clinical Solutions Pte Ltd.

Additional information: The e-Appendixes can be found in the “Supplemental Materials” area of the online article.

ANCOVA

analysis of covariance

CAT

COPD Assessment Test

GOLD

Global Initiative for Chronic Obstructive Lung Disease

IRB

institutional review board

MRC

Medical Research Council

SGRQ

St. George’s Respiratory Questionnaire

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Figures

Figure Jump LinkFigure 1. CAT scores by subgroups for characteristics for which the difference in mean scores between subgroups were significant. A, Mean CAT scores for BMI (kg/m2) < 18.5, ≥ 18.5, < 23.0, and ≥ 23.021 were 19.1, 18.7, and 15.2, respectively; P = .001. B, Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity classification based on the subject’s postbronchodilator FEV1 % predicted value: mean CAT scores for GOLD grade I, II, III, and IV were 16.5, 16.0, 19.0, and 21.3, respectively; P = .001. C, Mean CAT scores for 0, 1-2, ≥ 3 comorbidities (includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure [any cause], ischemic heart disease, on antihypertensive drugs, and on other cardiovascular drugs) were 17.7, 16.6, and 20.6, respectively; P = .054. D, Mean CAT scores for Hong Kong, Korea, Indonesia, and Vietnam were 13.9, 16.9, 18.1, and 19.3, respectively; P = .008. All mean scores were unadjusted for confounders. CAT = COPD Assessment Test.Grahic Jump Location
Figure Jump LinkFigure 2. A, Scatterplot of CAT scores and SGRQ Total scores. B, Scatter plot of CAT scores and SGRQ Activity scores. C, Scatter plot of CAT scores and SGRQ Symptoms scores. D, Scatter plot of CAT scores and SGRQ Impacts scores. SGRQ = St. George’s Respiratory Questionnaire. See Figure 1 legend for expansion of other abbreviation.Grahic Jump Location
Figure Jump LinkFigure 3. Scatterplot of CAT score to SGRQ total score by country with a regression line for each country. The slopes of regression lines are not significantly different by country (P = .759, interaction term for difference in the slopes when tested using ANCOVA analysis controlled for the country covariate). ANCOVA = analysis of covariance. See Figure 1 and 2 legends for expansion of other abbreviations.Grahic Jump Location

Tables

Table Graphic Jump Location
Table 1 —Demographic and Clinical Characteristics

Data are given as No. (%) unless otherwise indicated. GOLD = Global Initiative for Chronic Obstructive Lung Disease.

a 

GOLD severity classification based on the subject’s postbronchodilator FEV1 % predicted value.

b 

Includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure (any causes), ischemic heart disease, on antihypertensive drugs, on other cardiovascular drugs.

c 

Includes heart failure (any causes), ischemic heart disease, on antihypertensive drugs, on other cardiovascular drugs.

Table Graphic Jump Location
Table 2 —CAT Score and Measures of Impairment

CAT = COPD Assessment Test. See Table 1 legend for expansion of other abbreviation.

a 

The P value shows the test of significance between the mean CAT value of the classes of the characteristic using the one-way analysis of variance method.

b 

The P value is adjusted for age, BMI, sex, disease severity (GOLD severity classification based on the subject’s postbronchodilator FEV1 % predicted value), and country in a general linear model analysis with Bonferroni adjustments for multiple comparisons.

c 

Includes diabetes, peripheral artery diseases and rheumatoid disease, heart failure (any causes), ischemic heart disease, on antihypertensive drugs, and on other cardiovascular drugs.

d 

Includes heart failure (any causes), ischemic heart disease, on antihypertensive drugs, and on other cardiovascular drugs.

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