Introduction: The term quality of life has gained increasing importance in the scientific context. This study describes the adaptation of a disease-specific questionnaire developed by Paul Jones et al. in 1991, the St. George's Respiratory Questionnaire (SGRQ), to the Brazilian language and culture. This questionnaire evaluates the quality of life in patients with chronic obstructive pulmonary disease (COPD) and contains three domains (symptoms, activity, and impacts) divided in 76 items. The questionnaire is self-administrated, but it may be read to illiterate persons. Goal: To verify if the St. George's Respiratory Questionnaire is a valid tool to measure quality of life in patients with chronic obstructive pulmonary disease in Brazil. Methods: In order to validate the questionnaire in Brazil, it was initially translated into Portuguese and afterwards a back-translation into English, that was compared to the original version. A final Portuguese version was then written. This final version was, then, answered by 30 clinically stable COPD patients, according to the spirometry and oximetry values. Patients answered the questionnaire twice, within a 15 day interval. The length of time the patients took to answer the questionnaire and their doubts were noted. Wilcoxon test was used for the calculation of r probability between every single question between the two days; interclass correlation ratio was calculated to test the trustworthiness and reliability of the questionnaire. Results: Among the 30 participant patients, 10 were female and 20 were male. Mean age was 65.9 years. Most of the patients were found to be in stage 2 (56.7 %) of COPD, according to the American Thoracic Society classification. The interclass correlation ratio for the total score of the questionnaire was a = 0.79 and Wilcoxon p = 0.2110 (not statistically significant). The mean answering time for the two days of interview was, respectively, 11 minutes and 50 seconds and 10 minutes and 31 seconds. As concerns the doubts about the questions, the patients reported difficulties in answering Sections 4 and 5, each one of these questions written in a negative form. Conclusion: It can be concluded that the Brazilian version of the St. George's Respiratory Questionnaire is a valid and reliable tool to measure quality of life in patients with COPD in Brazil.

Keywords: obstructive lung diseases, questionnaire, quality of life, reproducibility of results, evolution studies

Introduction: A great emphasis has been placed on health-related quality of life of COPD patients and specific questionnaires have been developed in order to measure it. Interventions directed to improve symptoms and decrease morbi-mortality may be evaluated by such questionnaires. Objective: This study describes the language and cultural adaptation of a new (and short) disease-specific health status questionnaire developed for chronic obstructive pulmonary diseases: the Airways Questionnaire 20 (AQ20). This questionnaire has only 20 simple items, and is one of the shortest ones ever described in the literature. Methods: In order to validate this questionnaire in Brazil, an initial translation from English to Portuguese has been made. The cultural adaptation was taken into consideration and then a back translation to English was undertaken, in order to obtain a final Portuguese version. Correlations were made with FEV1, SpO2, BMI and another disease specific health status questionnaire, the Saint George Respiratory Questionnaire (SGRQ), previously validated in Brazil. To test the reproducibility of AQ20, the interclass correlation ratio was done. Results: The interclass correlation ratio for the total score was a = 0.90 (intraobserver variability) and a = 0.93 (interobserver variability). The correlation with total SGRQ score was 0.76, with p < 0.001. Conclusion: It can be concluded that the Brazilian Portuguese version of AQ20 is reproducible, with good correlation with SGRQ total score, which makes it a valid questionnaire to measure health status in obstructive patients in Brazil.