Validation and clinical interpretation of the St George's Respiratory Questionnaire among COPD patients, China

Although the St George's Respiratory Questionnaires in Mandarin-Chinese (SGRQ-MC) have been used in China, few data are available on the translation and adaptation process, psychometric properties and clinical meaning. It is therefore difficult to adequately evaluate the equivalence of this instrument in Chinese populations.

To evaluate the psychometric properties of a culturally translated SGRQ-MC, and to estimate clinically important differences (CID) for the SGRQ in chronic obstructive pulmonary disease (COPD) patients in China.

SGRQ was translated into Mandarin using standardised forward and backward translation procedures. Health status and clinical data were collected at baseline in 491 patients with stable COPD and again after 1 week in 131 randomly selected patients. All patients were followed up monthly and assessed during exacerbations and at 1 year.

The SGRQ-MC showed good internal consistency, test-retest reliability, convergent validity and known-group validity. Responsiveness was shown by significant changes in SGRQ-MC scores between stable stage and exacerbation (P<0.0001). The estimated CID for the total score ranged from 3.1 (95%CI -0.3-6.5) to 7.7 (95%CI -1.7-17.2).

This SGRQ-MC is a reliable, valid and responsive instrument for quality of life evaluation in COPD patients in China. As it is culturally and clinically equivalent to other versions, measures can be compared among countries.