Psychometric assessment of the Chinese language version of the St. George's Respiratory Questionnaire in Taiwanese patients with bronchial asthma

Background and purpose: The St. George's Respiratory Questionnaire (SGRQ) is a disease-specific quality-of-life instrument. It was designed to measure quality of life in obstructive pulmonary disease, and its reliability and validity have been demonstrated in different language versions. The purpose of this study was to determine the psychometric properties of a Chinese language version of the SGRQ in Taiwanese asthma patients. Methods: A convenient sample of 124 asthma patients were recruited from the outpatient asthma clinic of a teaching hospital in the Taipei area. The inclusion criteria were outpatient, coherent, and a clinical diagnosis of asthma. Patients with additional medical conditions considered to impact the quality of life were excluded. Three component scores (symptoms, activity, and impacts) and a total score were calculated to assess the SGRQ's psychometric characteristics. Data including demographic characteristics, history of emergency visits and hospital admissions, asthma severity, and quality of life were collected by questionnaires. Cronbach's formula for the α-coefficient was used to estimate the internal consistency and reliability of the SGRQ. Pearson's product-moment correlation was used to estimate the concurrent validity of the SGRQ. The discriminating validity of the SGRQ was determined by the t-test for independent samples. Results: Results showed that the SGRQ was internally consistent, and had good content and face validity. The SGRQ total score was significantly correlated with both the Health Index and the RAND 36-item Health Survey (p < 0.05). The SGRQ discriminated patients with respect to asthma severity (p < 0.001), history of prior emergency visits (p < 0.05), and history of prior hospital admissions (p < 0.05). Conclusions: This study demonstrated that the Chinese language version of the SGRQ has internal consistency and validity with strong evidence of content, concurrent, and discriminating validity in Taiwanese asthma patients. These findings suggest that it is a useful measure of quality of life in Taiwanese asthma patients.