Comparison of EQ-5D-5L, VAS, and SF-6D in Thai Patients on Peritoneal Dialysis

Abstract

Objectives: To compare the utility scores derived from the 5-level EuroQol 5-dimensional questionnaire (EQ-5D-5L), the visual analogue scale (VAS), and the 6-dimensional health state short form (SF-6D) in Thai patients on peritoneal dialysis.

Methods: Data were obtained from the 36-Item Kidney Disease Quality of Life questionnaire and the EuroQol questionnaires (EQ-5D-5L and VAS) via face-to-face interview for 64 patients on peritoneal dialysis. We compared the ceiling effect of all the utility tools by calculating the proportion at the highest scores. The mean difference in utility scores defined by patients' demographic characteristics and clinical laboratory value was evaluated using independent t tests or the Mann-Whitney U test. Moreover, the correlation was assessed using the Pearson correlation coefficient. The agreements among the instruments were illustrated with the Bland and Altman plots.

Results: The mean score of the EQ-5D-5L, SF-6D, and VAS were 0.801, 0.784, and 0.733, respectively. The EQ-5D-5L presented a higher percentage of the ceiling effect than did the SF-6D and VAS. The EQ-5D-5L was able to distinguish the mean difference between age groups with significant difference (P<.001). The Pearson correlation coefficients between utility scores and the 3 dimensions of the 36-Item Kidney Disease Quality of Life questionnaire had a significantly positive correlation, especially for the SF-6D. The Bland and Altman plots portrayed that the utility scores from the EQ-5D-5L were lower than those from the SF-6D and VAS among the patients in the poorer health state.

Conclusions: Among the SF-6D, EQ-5D-5L, and VAS, only the EQ-5D-5L could distinguish the utility scores between different age groups. Nevertheless, the EQ-5D-5L presented the ceiling effect, whereas there was no evidence of the ceiling effect for the SF-6D. The SF-6D presented better correlation with the kidney disease-specific dimensions than did the EQ-5D-5L and VAS. Thus, the advantages and disadvantages of each utility tool should be considered.

Keywords: EQ-5D-5L; SF-6D; VAS; peritoneal dialysis; quality of life; utility.