PATIENT-REPORTED OUTCOMES (PRO) OR QUALITY OF LIFE (QOL) STUDIES Validity and Reliability of KDQOL-36 in Thai Kidney Disease Patient

Objective: To evaluate the reliability and validity of the Thai version of the Kidney Disease Quality of Life 36 (KDQOL-36) questionnaire. The KDQOL-36 questionnaire consists of the short-form 12 health survey, and three dimensions of kidney disease questionnaires (the Symptom/ Problem List, Effects of Kidney Disease on Daily Life, and Burden of Kidney Disease). Methods: Subjects were 167 hemodialysis patients and 62 peritoneal dialysis patients. Reliability was evaluated by intraclass correlation coefficients for test-retest reliability assessment with face-to-face interview and Cronbach’s alpha for internal consistency. Construct validity was supported with convergent and discriminant validity by using correlation between six-dimensional health state short form (derived from short-form 36 health survey), the EuroQol five-dimensional questionnaire, the visual analogue scale parameter, and three dimensions of kidney disease questionnaires. Statistical analysis included descriptive statistics, Mann-Whitney U test, and Cronbach’s alpha. Results: Construct validity was satisfactory, with the significant difference being less than 0.001 between two groups (lowest through 25 percentile and higher than 75 percentile). The reliability coefficient for the Cronbach’s alpha of the total scale of the KDQOL-36 questionnaire was greater than 0.700 for all domains, ranging from 0.706 to 0.827. Intraclass correlation coefficients ranged from 0.713 to 0.999. Conclusion: The Thai version of the KDQOL-36 questionnaire is reliable and valid for evaluating the quality of life in Thai dialysis patients.