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Portuguese-language version of the COPD Assessment Test: validation for use in Brazil

Validação do Teste de Avaliação da DPOC em português para uso no Brasil

Guilherme Pinheiro Ferreira da Silva, Maria Tereza Aguiar Pessoa Morano, Cyntia Maria Sampaio Viana, Clarissa Bentes de Araujo Magalhães, Eanes Delgado Barros Pereira

ABSTRACT

Objective: To validate a Portuguese-language version of the COPD assessment test (CAT) for use in Brazil and to assess the reproducibility of this version. Methods: This was multicenter study involving patients with stable COPD at two teaching hospitals in the city of Fortaleza, Brazil. Two independent observers (twice in one day) administered the Portuguese-language version of the CAT to 50 patients with COPD. One of those observers again administered the scale to the same patients one week later. At baseline, the patients were submitted to pulmonary function testing and the six-minute walk test (6MWT), as well as completing the previously validated Portuguese-language versions of the Saint George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (MMRC) dyspnea scale, and hospital anxiety and depression scale (HADS). Results: Inter-rater and intra-rater reliability was excellent (intraclass correlation coefficient [ICC] = 0.96; 95% CI: 0.93-0.97; p < 0.001; and ICC = 0.98; 95% CI: 0.96-0.98; p < 0.001, respectively). Bland & Altman plots showed good test-retest reliability. The CAT total score correlated significantly with spirometry results, 6MWT distance, SGRQ scores, MMRC dyspnea scale scores, and HADS-depression scores. Conclusions: The Portuguese-language version of the CAT is a valid, reproducible, and reliable instrument for evaluating patients with COPD in Brazil.

Keywords: Pulmonary disease, chronic obstructive; Questionnaires; Validation studies; Quality of life; Reproducibility of results.

RESUMO

Objetivo: Realizar a validação e verificar a reprodutibilidade da versão em português do Brasil do COPD Assessment Test (CAT). Métodos: Estudo multicêntrico, no qual foram selecionados pacientes com DPOC estável em dois hospitais de ensino na cidade de Fortaleza, CE. A versão do CAT foi aplicada duas vezes a 50 pacientes com DPOC por dois observadores independentes no mesmo dia. Após uma semana, esse mesmo questionário foi aplicado novamente aos mesmos pacientes por um dos observadores. No primeiro dia, os pacientes foram submetidos à prova de função pulmonar e ao teste de caminhada de seis minutos (TC6) e responderam as versões validadas de Saint George's Respiratory Questionnaire (SGRQ), escala de dispneia Modified Medical Research Council (MMRC) e hospital anxiety and depression scale (HADS). Resultados: As reprodutibilidades interobservador e intraobservador foram excelentes (coeficiente de correlação intraclasse [CCI] = 0,96; IC95%: 0,93-0,97; p < 0,001; e CCI = 0,98; IC95%: 0,96-0,98; p < 0,001, respectivamente). As disposições gráficas de Bland & Altman demonstraram boa confiabilidade teste-reteste. Houve correlações significativas do escore total do CAT com os resultados de espirometria, TC6, SGRQ, escala de dispneia MMRC e HADS-depressão. Conclusões: A versão brasileira do CAT é um instrumento válido, reprodutível e confiável para a avaliação dos pacientes com DPOC na população brasileira.

Palavras-chave: Doença pulmonar obstrutiva crônica; Questionários; Estudos de validação; Qualidade de vida; Reprodutibilidade dos testes.

Introduction

Classically, COPD is defined as chronic progressive airflow limitation that is partially reversible and causes significant extrapulmonary effects, culminating in a reduction in the functional capacity, social interaction, and well-being of the patients, negatively affecting their health-related quality of life (HRQoL).(1,2)

The literature indicates that the chronic symptoms of COPD associated with the systemic manifestations of the disease are the major factors responsible for the worsening of HRQoL. Although the airflow obstruction is partially reversible, the disease control interventions are primarily aimed at improving the HRQoL of patients, which thereby becomes an important measure to be assessed.(3,4)

The administration of questionnaires to assess the HRQoL of patients with COPD has been widely discussed in the literature. The results inferred by the use of these instruments generate reliable, valid, and reproducible evidence.(5)

Disease-specific questionnaires designed to assess COPD impact are widely used in clinical studies. However, these questionnaires are still considered complex and extensive, requiring a substantial amount of time to completion. Chief among them are the Saint George's Respiratory Questionnaire (SGRQ),(6) the Chronic Respiratory Questionnaire (CRQ),(7) the Breathing Problems Questionnaire,(8) and the Airways Questionnaire 20 (AQ20),(9) all of which have been validated for use in Brazil.

Recently, a group of researchers in the United Kingdom developed and validated the COPD Assessment Test (CAT), which is a short, simple instrument for quantifying COPD impact during routine clinical practice, in addition to aiding health status assessment and facilitating communication between patients and health professionals.(10) However, this questionnaire has not been validated for use in Brazil. Therefore, the objective of the present study was to validate a Portuguese-language version of the CAT for use in Brazil and to assess the reproducibility of this version.

Methods

This was a cross-sectional study, conducted between January and November of 2012, involving patients treated at the Pulmonology Outpatient Clinic of the Federal University of Ceará Walter Cantídio University Hospital and patients eligible for pulmonary rehabilitation at the Dr. Carlos Alberto Studart Gomes Messejana Hospital, both of which are located in the city of Fortaleza, Brazil.

The present study was conducted in accordance with Brazilian National Health Council Resolution 196/96, which sets out the ethical principles for human research, and was approved by the ethics committees of the two hospitals (Ruling no. 108.10/11 and Ruling no. 880/12, respectively). All patients gave written informed consent prior to their inclusion in the study.

The inclusion criteria were as follows: having been clinically diagnosed with COPD with moderate to severe airflow obstruction and having an FEV1/FVC ratio < 0.7 (as measured by spirometry), in accordance with the recommendations of the Global Initiative for Chronic Obstructive Lung Disease(1); being between 40 and 80 years of age; being clinically stable (no hospitalizations or infections in the three months prior to the study); and being a smoker or former smoker with a smoking history greater than 10 pack-years.

The exclusion criteria were as follows: experiencing an exacerbation of COPD requiring therapeutic intervention; and having other nonpulmonary diseases that are considered disabling, severe, or difficult-to-control.

The CAT consists of eight items, designated cough, phlegm, chest tightness, breathlessness, activity limitations at home, confidence leaving home, sleep, and energy. For each item, the patient chooses only one response option, which is scored from zero to five (Appendix 1). At the end of the test, all response scores are summed, and then the clinical impact of COPD is determined on the basis of the stratification scoring of the study that developed and validated the CAT.(10) The results vary according to the range within which the scores obtained lie, being classified by clinical impact as follows: 6-10 points, mild; 11-20, moderate; 21-30, severe; and 31-40, extremely severe.



In order to test the inter-rater reliability of the CAT, the patients were administered the questionnaire twice by two observers, 30 minutes apart, during the first visit (V1). The second visit (V2) occurred 7 days after the first one, and the CAT was again administered to the same patients by only one of the observers in order to test the intra-rater reliability.

Also at baseline, the patients underwent the six-minute walk test (6MWT) and spirometry, as well as being administered the previously validated Portuguese-language versions of the SGRQ,(6) hospital anxiety and depression scale (HADS), and modified Medical Research Council (MMRC) dyspnea scale.

Spirometry was performed with a Respiradyne II Plus spirometer (Sherwood Medical, St. Louis, MO, USA), in accordance with Brazilian guidelines,(11) using the reference values for the Brazilian population established by Pereira et al.(12)

The 6MWT was performed in accordance with guidelines established by the American Thoracic Society,(13) with the patient being encouraged to walk as far as possible, in six minutes, on a 30-m level corridor. At the end of the test, the examiner recorded the distance covered.

The HADS consists of 14 items, of which 7 focus on the assessment of anxiety (HADS-A) and 7 focus on the assessment of depression (HADS-D). Each item can be scored from zero to three, the maximum score on each subscale being 21 points. We adopted the cut-off points recommended for both subscales: 0-8 points, absence of anxiety and/or depression; and  9 points, presence of anxiety and/or depression.(14)

Dyspnea was assessed with the MMRC dyspnea scale.(11)

Data were statistically analyzed with the Statistical Package for the Social Sciences, version 17.0 (SPSS Inc., Chicago, IL, USA) and GraphPad Prism, version 6.0 (GraphPad Software Inc., San Diego, CA, USA). For the analysis of the reliability of the administration of the CAT (V1 vs. V2), we used the intraclass correlation coefficient (ICC). The Wilcoxon test was used to compare the scores obtained from the administration of the CAT by the observer in V1 and V2. In order to assess the agreement between V1 and V2, we used Bland & Altman plots. The instruments were tested for internal consistency by Cronbach's alpha coefficient. In order to validate the CAT, we assessed the correlations (Spearman's correlation test) of its scores with those obtained on the SGRQ (gold standard questionnaire), HADS, and MMRC dyspnea scale, as well as with 6MWD and spirometry values. The level of significance was set at 5%.

Results

The study sample comprised 50 patients with COPD, 26 of whom were female (52%). The mean age of the patients was 62.2 ± 8.4 years, whereas the mean height and weight were 1.58 ± 0.08 cm and 65.8 ± 15.9 kg, respectively.

There were no significant differences between the total scores obtained from the administration of the CAT by the same observer in V1 and V2 (20.7 ± 9.8 vs. 20.1 ± 9.4; p = 0.8). The ICC for intra-rater reliability (V1 vs. V2) was 0.96 (95% CI: 0.93-0.97).

There were also no significant differences in the scores between the two observers of the study (20.7 ± 8.5 vs. 21.2 ± 9.0; p = 0.4). The ICC for inter-rater reliability was 0.98 (95% CI: 0.96-0.98). The Cronbach's alpha coefficient for the CAT was 0.98 (p < 0.001).

Bland & Altman plots showed good test-retest reliability and good inter-rater reliability (Figure 1).



There were significant correlations between the CAT score and the SGRQ total and domain scores (0.51 < r < 0.64). The CAT score correlated better with the MMRC dyspnea scale score than with the HADS-D score (r = 0.48 vs. r = 0.39; p < 0.05 for both). The CAT scores correlated negatively with 6MWD (r = −0.37) and with some pulmonary function measurements, such as FEV1 in L (r = −0.38); FVC in L (r = −0.39); and FVC as % of the predicted value (r = −0.30; Table 2).





The mean administration time was 104.00 ± 0.69 seconds.

Discussion

The present study showed that the Portuguese-language version of the CAT had excellent reliability when administered by different observers and when administered by the same observer at two distinct time points. Bland & Altman plots showed that the CAT has good test-retest reliability, as well as a high Cronbach's alpha coefficient and a good correlation with the SGRQ (total and domain scores).

The process of development and preparation of the CAT arose from the need for new instruments for evaluating COPD impact on HRQoL and clinical practice in a simple, fast, and effective way.(10)

Various studies conducted in countries such as Spain,(15) China,(16) South Korea,(17) and Saudi Arabia(18,19) have validated versions of the CAT in their language and reported the instrument to have good reproducibility. We found no studies validating a Portuguese-language version of the CAT for use in Brazil or assessing the reproducibility of the CAT.

During test-retest, the ICC was found to be 0.98. Jones et al.(10) found high ICC values and high Cronbach's alpha coefficients when they performed the first validation of the CAT in a multicenter study. The Cronbach's alpha coefficient of 0.98 found in the present study shows that the questionnaire has excellent internal consistency.

The questionnaires used for the validation of the CAT were the SGRQ, MMRC dyspnea scale, and HADS. These instruments were used because they are related to some specific items of the CAT, such as those concerning respiratory symptoms and limitations in activities of daily living (which are also addressed in the SGRQ and MMRC dyspnea scale) and those concerning self-confidence and energy (which are also addressed in the HADS and SGRQ).

In general, there were high and significant correlations between the CAT scores and the SGRQ total and domain scores.

Previous studies have demonstrated that the CAT can measure the impact of COPD on the lives of patients, showing correlations with standard questionnaires other than the SGRQ, such as the CRQ and the Clinical COPD Questionnaire.(20-24)

Regarding the pulmonary function variables, the present study showed that there was a weak but significant correlation of the CAT scores with some spirometry values and 6MWD. This might represent a discrepancy between patient experiences and perspectives and the degree of respiratory dysfunction. Other studies have also shown weak correlations between the CAT scores and pulmonary function values, especially FEV1.(17,20,21,25)

Regarding the sensation of dyspnea, the CAT scores correlated significantly with MMRC dyspnea scale scores and SGRQ symptom scores, showing that the CAT can detect the patient's respiratory complaints.

There was no significant correlation between the CAT scores and the anxiety scores. However, for the depression scores, the correlation was found to be weak. This might have occurred because, among the CAT questions, only the items concerning energy and confidence leaving home address issues that are more directly related to the psychological component of the patient.

The administration time of the CAT in the present study was, on average, 104 s; this occurred because of the simplicity of the questions and response options. While administering the CAT to patients with COPD, Ringbaek et al.(26) found that it required a shorter administration time than did the SGRQ and CRQ (107 s, 134 s, and 578 s, respectively).

There was no back-translation analysis of the CAT, since there is already a Portuguese-language version, written in congruent, easy-to-understand language, ready for use. None of the items in the present version sounded odd in Brazilian Portuguese or seemed to be alien to the Brazilian culture and society, and therefore there was no need for any significant adaptations.

Since the present study was cross-sectional in design, it was not possible to evaluate the responsiveness of the Portuguese-language version of the CAT to interventions, such as pulmonary rehabilitation. This can be considered a limitation of the study; however, other studies have used the same approach.(15,21,23,26) Following this line of thought and knowing that the Portuguese-language version of the CAT proved to be valid and reproducible, we believe that, in future studies, it will prove to be responsive.

In conclusion, the Portuguese-language version of the CAT is a valid, reproducible, and reliable instrument for assessing the impact of COPD on the lives of patients in Brazil.

References

1. Rabe KF, Hurd S, Anzueto A, Barnes PJ, Buist SA, Calverley P, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary. Am J Respir Crit Care Med. 2007;176(6):532-55. http://dx.doi.org/10.1164/rccm.200703-456SO PMid:17507545

2. Agusti A, Calverley PM, Celli B, Coxson HO, Edwards LD, Lomas DA, et al. Characterisation of COPD heterogeneity in the ECLIPSE cohort. Respir Res. 2010;11:122. PMid:20831787 PMCid:2944278

3. Barnes PJ, Celli BR. Systemic manifestations and comorbidities of COPD. Eur Respir J. 2009;33(5):1165-85. http://dx.doi.org/10.1183/09031936.00128008 PMid:19407051

4. Ng TP, Niti M, Tan WC, Cao Z, Ong KC, Eng P. Depressive symptoms and chronic obstructive pulmonary disease: effect on mortality, hospital readmission, symptom burden, functional status, and quality of life. Arch Intern Med. 2007;167(1):60-7. http://dx.doi.org/10.1001/archinte.167.1.60 PMid:17210879

5. Ferreira CA, Cukier A. Evaluating COPD from the perspective of the patient. J Bras Pneumol. 2006;32(2):vii-viii. PMid:17273576

6. Sousa TC, Jardim JR, Jones P. Validação do Questionário do Hospital Saint George na Doença Respiratória (SGRQ) em pacientes portadores de doença pulmonar obstrutiva crônica no Brasil. J Pneumol. 2000; 26(3):119-28. http://dx.doi.org/10.1590/S0102-35862000000300004

7. Moreira GL, Pitta F, Ramos D, Nascimento CS, Barzon D, Kovelis D, et al. Portuguese-language version of the Chronic Respiratory Questionnaire: a validity and reproducibility study. J Bras Pneumol. 2009;35(8):737-44. http://dx.doi.org/10.1590/S1806-37132009000800004 PMid:19750325

8. Silva PN, Jardim JR, Costa e Souza GM, Hyland ME, Nascimento OA. Cultural adaptation and reproducibility of the Breathing Problems Questionnaire for use in patients with COPD in Brazil. J Bras Pneumol. 2012;38(3):339-45. Erratum in: J Bras Pneumol. 2012;38(4):538. http://dx.doi.org/10.1590/S1806-37132012000300009 PMid:22782604

9. Camelier A, Rosa F, Jones P, Jardim JR. Validação do questionário de vias aéreas 20 ("Airways questionnaire 20" - AQ20) em pacientes portadores de doença pulmonar obstrutiva crônica (DPOC) no Brasil. J Pneumol. 2003;29(1):28-35.

10. Jones PW, Harding G, Berry P, Wiklund I, Chen WH, Kline Leidy N. Development and first validation of the COPD Assessment Test. Eur Respir J. 2009;34(3):648-54. http://dx.doi.org/10.1183/09031936.00102509 PMid:19720809

11. Sociedade Brasileira de Pneumologia e Tisiologia. II Consenso Brasileiro de Doença Pulmonar Obstrutiva Crônica (DPOC) - 2004. J Bras Pneumol. 2004;30(5):1-42.

12. Pereira CA, Barreto SP, Simoes JG, Pereira FW, Gerstler JG, Nakatami J. Valores de referência para a espirometria em uma amostra da população brasileira adulta. J Pneumol. 1992;18(1):10-22.

13. Brooks D, Solway S, Gibbons WJ. ATS statement on six-minute walk test. Am J Respir Crit Care Med. 2003;167(9):1287. http://dx.doi.org/10.1164/ajrccm.167.9.950 PMid:12714344

14. Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta Psychiatr Scand. 1983;67(6):361-70. http://dx.doi.org/10.1111/j.1600-0447.1983.tb09716.x

15. Agustí A, Soler JJ, Molina J, Mu-oz MJ, García-Losa M, Roset M, et al. Is the CAT questionnaire sensitive to changes in health status in patients with severe COPD exacerbations? COPD. 2012;9(5):492-8. http://dx.doi.org/10.3109/15412555.2012.692409 PMid:22958111

16. Wiklund I, Berry P, Lu KX, Fang J, Fu C. The Chinese translation of COPD Assessment TestT (CAT) provides a valid and reliable measurement of COPD health status in Chinese COPD patients. Am J Respir Crit Care Med 181;2010:A3575.

17. Lee S, Lee JS, Song JW, Choi CM, Shim TS, Kim TB, et al. Validation of the Korean version of Chronic Obstructive Pulmonary Disease Assessment Test (CAT) and Dyspnea-12 Questionnaire. Tuberc Respir Dis. 2010;69(3):171-6. http://dx.doi.org/10.4046/trd.2010.69.3.171

18. Al-Moamary MS, Al-Hajjaj MS, Tamim HM, Al-Ghobain MO, Al-Qahtani HA, Al-Kassimi FA. The reliability of an Arabic translation of the chronic obstructive pulmonary disease assessment test. Saudi Med J. 2011;32(10):1028-33. PMid:22008922

19. Al Moamary MS, Tamim HM, Al-Mutairi SS, Al-Khouzaie TH, Mahboub BH, Al-Jawder SE, et al. Quality of life of patients with chronic obstructive pulmonary disease in the Gulf Cooperation Council countries. Saudi Med J. 2012;33(10):1111-7. PMid:23047217

20. Jones PW, Price D, van der Molen T. Role of clinical questionnaires in optimizing everyday care of chronic obstructive pulmonary disease. Int J Chron Obstruct Pulmon Dis. 2011;6:289-96. http://dx.doi.org/10.2147/COPD.S18181 PMid:21697993 PMCid:3119104

21. Tsiligianni IG, van der Molen T, Moraitaki D, Lopez I, Kocks JW, Karagiannis K, et al. Assessing health status in COPD. A head-to-head comparison between the COPD assessment test (CAT) and the clinical COPD questionnaire (CCQ). BMC Pulm Med. 2012;12:20. http://dx.doi.org/10.1186/1471-2466-12-20 PMid:22607459 PMCid:3431277

22. Weldam SW, Schuurmans MJ, Liu R, Lammers JW. Evaluation of Quality of Life instruments for use in COPD care and research: a systematic review. Int J Nurs Stud. 2013;50(5):688-707. http://dx.doi.org/10.1016/j.ijnurstu.2012.07.017 PMid:22921317

23. Dodd JW, Marns PL, Clark AL, Ingram KA, Fowler RP, Canavan JL, et al. The COPD Assessment Test (CAT): short- and medium-term response to pulmonary rehabilitation. COPD. 2012;9(4):390-4. PMid:22497561

24. Mackay AJ, Donaldson GC, Patel AR, Jones PW, Hurst JR, Wedzicha JA. Usefulness of the Chronic Obstructive Pulmonary Disease Assessment Test to evaluate severity of COPD exacerbations. Am J Respir Crit Care Med. 2012;185(11):1218-24. http://dx.doi.org/10.1164/rccm.201110-1843OC PMid:22281834

25. Ghobadi H, Ahari SS, Kameli A, Lari SM. The relationship between COPD Assessment Test (CAT) scores and severity of airflow obstruction in stable COPD patients. Tanaffos. 2012;11(2):22-6

26. Ringbaek T, Martinez G, Lange P. A comparison of the assessment of quality of life with CAT, CCQ, and SGRQ in COPD patients participating in pulmonary rehabilitation. COPD. 2012;9(1):12-5. http://dx.doi.org/10.3109/15412555.2011.630248 PMid:22292593



*Study carried out at the Federal University of Ceará and at the Dr. Carlos Alberto Studart Gomes Messejana Hospital, Fortaleza, Brazil.
Correspondence to: Eanes Delgado Barros Pereira, Rua Barbara de Alencar, 1401, CEP 60140-000, Fortaleza, CE, Brasil.
Tel. 55 85 494-9000. E-mail: eanes@fortalnet.com.br
Financial support: This study received financial support from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Office for the Advancement of Higher Education).
Submitted: 22 January 2013. Accepted, after review: 7 May 2013.




About the authors

Guilherme Pinheiro Ferreira da Silva
Physical Therapist. Hospital Distrital Gonzaga Mota - José Walter, Fortaleza City Hall, Fortaleza, Brazil.

Maria Tereza Aguiar Pessoa Morano
Head. Department of Pulmonary Rehabilitation, Dr. Carlos Alberto Studart Gomes Messejana Hospital, Fortaleza, Brazil.

Cyntia Maria Sampaio Viana
Pulmonologist. Department of Pulmonary Rehabilitation, Dr. Carlos Alberto Studart Gomes Messejana Hospital, Fortaleza, Brazil.

Clarissa Bentes de Araujo Magalhães
Resident in Physical Therapy/Intensive Care. Federal University of Ceará, Fortaleza, Brazil.

Eanes Delgado Barros Pereira
Associate Professor. Department of Clinical Medicine and Master's Program in Medical Sciences, Federal University of Ceará, Brazil.

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