A comparison of three measures: the time trade-off technique, global health-related quality of life and the SF-36 in dialysis patients

We investigated the correlation between descriptive and valuational measure s of health-related quality of life (HRQL) and assessed determinants affect ing these measures. Our suspicion was that there is little similarity in th e content of descriptive and valuational measures of HRQL. We thus conducte d a cross-sectional observational study of 56 hemodialysis patients. All un derwent structured interviews. Dependent variables were patients utilities [time trade-off (TTO)], global rating of HRQL and generic HRQL (SF-36). Ind ependent variables were socioeconomic details, disease severity, comorbidit y, symptoms, depression, social support, and laboratory data. The correlati on between TTO and global HRQL was -0.33 (P = .0178) and between TTO and th e SF-36 physical and mental summary scores -0.16 (P = .2383) and -0.20 (P = .1443), respectively. The regression models for the SF-36 physical and men tal summary scores explained 75% and 64% of the variance, and for global HR QL 29% of the variance. The independent variables had no effect on the TTO. This confirmed our suspicion that a qualitative difference exists between TTO and descriptive quality of life tools. The TTO content could not be exp lained by the variables that entail the content of HRQL instruments. (C) 20 01 Elsevier Science Inc. All rights reserved.