The COPD assessment test and St George's Respiratory Questionnaire: are they equivalent in subjects with COPD?

Mariko Morishita-Katsu,1,2 Koichi Nishimura,3 Hiroyuki Taniguchi,1 Tomoki Kimura,1 Yasuhiro Kondoh,1 Kensuke Kataoka,1 Tomoya Ogawa,4 Fumiko Watanabe,4 Shinichi Arizono,5 Osamu Nishiyama,6 Kazuhito Nakayasu,7 Kazuyoshi Imaizumi,8 Yoshinori Hasegawa2 1Department of Respiratory Medicine and Allergy, Tosei General Hospital, Seto, Japan; 2Division of Respiratory Medicine, Department of Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan; 3Department of Pulmonary Medicine, National Center for Geriatrics and Gerontology, Obu, Japan; 4Department of Rehabilitation, Tosei General Hospital, Seto, Japan; 5School of Rehabilitation Sciences, Seirei Christopher University, Hamamatsu, Japan; 6Department of Respiratory Medicine and Allergology, Kinki University School of Medicine, Osakasayama, Japan; 7Data Research Section, Kondo P.P. Inc., Osaka, Japan; 8Department of Respiratory Medicine, Fujita Health University, Nagoya, Japan Background: The chronic obstructive pulmonary disease (COPD) assessment test (CAT) is a short questionnaire that has facilitated health status measurements in subjects with COPD. However, it remains controversial as to whether the CAT can be used as a suitable substitute for the St George’s Respiratory Questionnaire (SGRQ). This study investigated the reliability and score distributions of the CAT and SGRQ and evaluated which factors contributed to health status for each questionnaire.Methods: A total of 109 consecutive subjects with stable COPD from a single center were enrolled in this study. Each subject completed pulmonary function tests, exercise tests, and the following self-administered questionnaires: the Baseline Dyspnea Index, the Hospital Anxiety and Depression Scale, the CAT, and SGRQ.Results: Internal consistencies of CAT and SGRQ total scores were both excellent (Cronbach’s α coefficients =0.890 and 0.933). Statistically significant correlations were observed between CAT and SGRQ total scores (R=0.668, P<0.001). Correlations of CAT scores with parameters related to pulmonary function, dyspnea, exercise performance, and psychological factors were inferior to correlations with those parameters with SGRQ total scores. Both multiple regression analyses and principal component analyses revealed that there were slight differences between SGRQ total scores and CAT scores.Conclusion: The CAT is similar to SGRQ in terms of discriminating health status. However, we demonstrated that what is assessed by the CAT may differ slightly from what is measured by SGRQ. Keywords: chronic obstructive pulmonary disease, St George’s Respiratory Questionnaire, COPD assessment test, health statu