Determining the validity and reliability of the Chinese version of the Kidney Disease Quality of Life Questionnaire (KDQOL-36™)

BACKGROUND Health-related quality of life is a crucial outcome for the chronic kidney disease population, the Kidney Disease Quality of Life (KDQOL) questionnaire is commonly used as an integral part of clinical evaluations. The abbreviated version of the KDQOL-36™ has been translated into Mandarin Chinese, but has not been tested for use in the Chinese patients. The aim of the study was to evaluate the validity and reliability of the KDQOL-36™ with a sample of Chinese patients. METHODS The Mandarin Chinese version of the KDQOL-36™ has been translated by Amgen, Inc. and the MAPI Institution following the instrument translation specifications provided by the RAND health. The translated instrument was further reviewed by a Chinese expert panel for content validity and translational equivalence. The KDQOL-36™ along with Beck depression Inventory-II were administrated to 103 chronic renal disease patients recruited through convenience sampling procedure from the renal wards and an outpatient dialysis clinic. The convergent validity was determined through investigating the correlational evidence of the KDQOL-36™ with the Beck depression Inventory-II and the overall health rating. Known-group validity was supported by the evidence that the instrument could differentiate subgroups of patients. The internal consistency was estimated using Cronbach's α and test-retest reliability was examined using an intraclass correlation coefficient. RESULTS For the convergent validity, there were positive correlations between the overall health rating and most of the KDQOL-36™ subscales, and the Beck depression inventory score was inversely correlated with the mental component summary score and disease-specific scores of the scale. Significant correlations were noted between disease-targeted and generic dimensions of the KDQOL-36™. The results of the known-group comparisons indicated females, the unemployed, and patients had a longer dialysis history reported a worse quality of life. With regard to the reliability, the Cronbach's alpha ranged from 0.69 to 0.78, and the intraclass correlation test-retest was higher than 0.70. CONCLUSIONS The Mandarin Chinese version of the KDQOL-36™ is a brief, valid, and reliable instrument for use in examining the quality of life of chronic kidney disease patients in China.