Reliability and validity of the St George's Respiratory Questionnaire for asthma

BACKGROUND: The St George's Respiratory Questionnaire (SGRQ) is a self-administered questionnaire that has been used to evaluate the health-related quality of life of patients with chronic respiratory diseases. OBJECTIVE: To assess the validity and reliability of the SGRQ for a large population with asthma. DESIGN: We used the previously developed Korean version of the SGRQ (SGRQ-K) to assess 676 asthma patients enrolled from the Cohort for Reality and Evolution of Adult Asthma in Korea study. Cronbach's alpha was used to assess test reliability and Pearson's correlation coefficient was used to assess the correlation between SGRQ scores and various clinical factors. RESULTS: The total SGRQ-K score had acceptable reliability (Cronbach's alpha = 0.92). The total SGRQ-K score was significantly correlated with symptom duration (r = 0.157, P < 0.001), pulmonary function (% FEV1 of predicted r = 0.314, P < 0.001; % FVC of predicted r = -0.224, P < 0.001; FEV1/FVC r = 0.224, P < 0.001), asthma severity (r = 0.278, P < 0.001) and history of asthma exacerbation. CONCLUSION: With the exception of the SGRQ-K symptoms, SGRQ-K is a reliable and valid test for evaluation of the quality of life of patients with asthma. Scores were well correlated with duration of symptoms, lung function and previous history of asthma exacerbation.