Development and psychometric properties of the dialysis module of the WHOQOL-BREF Taiwan version.

BACKGROUND: Quality of life (QOL) is now considered to be an important part of the assessment of dialysis patients. The aim of this study was to develop and assess the reliability, validity and sensitivity of the dialysis module of the World Health Organization Quality of Life - Brief (WHOQOL-BREF) Taiwan version [WHOQOL-BREF(TW)] in patients undergoing regular hemodialysis (HD). METHODS: QOL survey was administered to 283 regular HD patients in metropolitan Taipei. The instruments used included: (1) the proposed module - composed of the core part, the WHOQOL-BREF(TW), and the six specific items; (2) the symptom/problem (S/P) scale - composed of 12 items specific for dialysis patients; (3) the utility measure, which was performed with standard gamble (SG) methods; and (4) the rating scale (RS). RESULTS: Based on the six criteria of validity, reliability and variance of the items, four HD-specific items were selected. Reliability study showed that Cronbach's alphas, composite reliability, and test-retest reliability (intraclass correlation at an average retest interval of 4-8 weeks) of the four domains of physical, psychological, social relationship and environment, ranged from 0.74-0.82, 0.79-0.84 and 0.61-0.79, respectively. Validity study showed that all the correlations between an item and its corresponding domain were highly significant (r>0.4, p<0.01) and larger than the correlations between the item and other domains. SG and psychometric measures showed relatively low correlations (0.12-0.26). The module showed the same construct as the WHOQOL-BREF(TW) under confirmatory factor analysis, whereas the exploratory factor analysis showed mild variation. Convergent and discriminant validity were good. Global QOL, physical, psychological and environment domains had some sensitivity to differentiate the severity of the condition of patients receiving HD. Clinical validity was demonstrated in global QOL, physical and psychological domains to have significant correlations with S/P scores. CONCLUSION: Besides broader coverage than the core WHOQOL-BREF(TW), the dialysis module of the WHOQOL-BREF(TW) is a valid, reliable and sensitive QOL instrument for the assessment of HD patients in Taiwan.