Reliability and construct validity of the Chinese (Hong Kong) SF-36 patients in primary care

Abstract

Objective: To assess the internal and test-retest reliability, and construct validity of the Chinese (Hong Kong) SF-36 for patients in primary care. Design: Cross-sectional questionnaire face-to-face interviews and retest by telephone interviews. Subjects: 500 Chinese patients aged 18 or above attending a government general outpatient primary care clinic in Hong Kong. Main outcome measure: Internal reliability was measured by Cronbach's alpha. Test-retest reliability was measured by the difference between test-retest scores and intraclass correlation. Construct validity was assessed by the correlations between the Chinese (Hong Kong) SF-36 scores and the Chinese COOP/WONCA Chart scores, and the correlation between the Chinese (Hong Kong) SF-36 scores and the total number of chronic diseases. Results: Internal reliability coefficients of all the Chinese (Hong Kong) SF-36 scales exceeded 0.7; there was no clinically important difference between test-retest scores of the Chinese (Hong Kong) SF-36. The expected correlations were observed between the Chinese (Hong Kong) SF-36 scores and the COOP/WONCA Chart scores. There was a negative correlation between the total number of chronic diseases and the scores of five scales of the Chinese (Hong Kong) SF-36. Conclusion: The Chinese (Hong Kong) SF-36 was reliable for group comparison and had good convergent and divergent construct validity for patients in primary care.