EVALUATION OF UTILITY INDEX OF QUALITY OF LIFE (QOL) IN PROSTATE CANCER PATIENTS: COMPARISON OF QOL UTILITY INDEX EuroQol-5D (EQ-5D) AND VISUAL ANALOGUE SCALE (VAS) WITH HEALTH-RELATED QOL QUESTIONNAIRES SF-36 AND EPIC

(Purpose) For the management of patients with localized prostate cancer, a number of therapeutic options are available. To compare the therapeutic modalities, it is important and necessary to evaluate economical aspects based on cost-effectiveness analysis. In addition, the survival time adjusted by quality of life (QOL), quality adjusted life year (QALY), is more reliable than the crude survival time. Thus, the usefulness of the commonly used QOL utility indexes, EuroQol-5D (EQ-5D) and visual analogue scale (VAS, 0-100 points), was investigated in prostate cancer patients. (Patients and methods) A total of 81 patients with prostate cancer were included. The patients were asked to answer the four sets of questionnaires (EQ-5D, VAS, SF-36 and EPIC). The QOL utility indexes (EQ-5D and VAS) were evaluated in relation to the general and prostate cancer-specific QOL questionnaires (SF-36 and EPIC, respectively). (Results) The results of EQ-5D and VAS were significantly correlated to all domains of the general QOL questionnaire (SF-36). On the contrary, no remarkable relationship of EQ-5D and VAS was observed with any domain (urinary, bowel, sexual or hormonal) of the prostate cancer-specific QOL questionnaire (EPIC). There was significant and close correlation between the actual values of VAS and the estimates of VAS calculated from SF-36 data (R=0.53, p