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

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.