Validation and clinical interpretation of the St George’s respiratory questionnaire for COPD (SGRQ-C) after adaptation to Malaysian language and culture, in patients with COPD

Abstract

Background

Cultural differences affect the administration and results of health status questionnaires. “Cross cultural adaptation” ensures retention of psychometric properties such as validity and reliability at an item and/or scale level.

Objective

To develop a Malaysian version of St George’s respiratory COPD specific questionnaire (SGRQ-CM), to evaluate the full spectrum of psychometric properties (reliability, validity and responsiveness), to test the factor structure and to assess minimum clinically important difference for the SGRQ-CM, to be used in population of Malaysia.

Methodology

SGRQ-C was translated to Bahasa Malaysia using a standard protocol. 240 COPD patients were included in the study. All patients were followed-up for six months. Construct validity, internal consistency, item convergent validity, test-retest ability, responsiveness, factor analysis and MCID of the Malaysian version of SGRQ-C to be used in population of Malaysia were evaluated.

Results

The Cronbach alpha coefficient and intraclass correlation coefficients (ICC) for SGRQ-CM were reported as 0.87, and 0.88 respectively. Correlation of SGRQ-CM with CAT, EQ-5D-5 L, mMRC dyspnea scales and FEV₁%predicted were reported as 0.86, − 0.82, 0.72 and − 0.42 respectively. Correlation coefficient between the subscales and other clinical and health status measures ranged from r = − 0.35 to r = − 0.87. The MCID was reported as 5.07 (− 2.54–12.67).

Conclusion

The Malaysian version of SGRQ-C has a good psychometric property comparable to those of the original version and has a strong evidence of validity, reliability and responsiveness towards disease severity in Malaysian COPD patients. It can be recommended as a reliable quality of life measure for future research.