Validity and specificity of the Persian version of the Saint George Respiratory Questionnaire.

INTRODUCTION

The Saint George Respiratory Questionnaire (SGRQ) is a well-known questionnaire for evaluating the quality of life in asthmatic patients. It has been translated to Persian and its validity and specificity should be evaluated for chronic obstructive pulmonary disease patients. In this study, we attempted to improve the questionnaire's adaptability to Persian culture and also evaluate its validity, specificity, and applicability among asthmatics at our tertiary referral center.

MATERIALS AND METHODS

Previously translated and psychometrically evaluated SGRQ for chronic obstructive pulmonary disease patients was made more adaptive to Persian. Upon acceptability of the questionnaire by a small group of patients, 301 asthmatics referred for spirometry and completed the form. Consistency was evaluated using Cronbach's α coefficient and validity was assessed by comparison of scores with other measures of asthma exacerbation. These measures included FEV1, patient's clinical presentation, visual analog scale (used to assess difficulty breathing), Katz activity index and section scores of the General Health Questionnaire, anxiety, depression, and social impact.

RESULTS

The study group included 165 female and 139 male asthmatics with a mean age of 44.4 ± 1.0 years. Measurement of consistency for the SGRQ revealed Cronbach's α to be 0.699 for symptoms, 0.805 for activity, 0.879 for impact, and 0.916 for the total questionnaire. By omitting question 8, time of wheezing during the day increased Cronbach's coefficient of the symptoms section to 0.719. Omitting "uselessness of respiratory drugs" from the impact section increased Cronbach's α to 0.881. However, scoring of the section then varied from the original questionnaire. A statistically significant correlation was found between the SGRQ sections and total score (using Katz index and General Health Questionnaire, p < .001).

CONCLUSION

Our study showed good validity and reliability for the Persian version of SGRQ for a population of asthmatics referred to our tertiary pulmonary clinic.