Comparison and validation of EuroQol-5 Dimension level and Short Form-6 Dimension in cataract patients

Abstract

Background: EuroQol-5 Dimension (EQ-5D) and Short Form-6 dimension (SF-6D) are instruments that have been widely used to assess utility index as an outcome parameter in pharmacoeconomic studies. The choice of an instrument will have an important effect and can influence the decision making of an economic health evaluation. Objectives: The aim of this study was to compare the SF-6D and EQ-5D instruments to assess utility index in cataract patients. Methods: The study was conducted with on 448 cataract patients in a hospital in Yogyakarta. The subjects of the study were outpatient cataract patients over 45 years of age. The patient's health-related quality of life (HRQoL) was assessed using the SF-6D, EQ-5D, and visual function questionnaire instruments. The construct validity was tested including known group validity using the independent sample t test and ANOVA, convergent validity with the Spearman correlation, ceiling effect, and bland and Altmand plots. Results: A total of 448 cataract patients, mean age 64.7 (10.1) years, showed utility index assessed using the EQ-5D-5L and SF-6D instruments, which were 0.7 (0.2) and 0.8 (0.1), respectively. Convergent validity shows that the EQ-5D-5L dimensions have a moderate to very strong correlation (0.4-0.9) with the dimensions on VFQ-25, as well as the SF-6D (0.4-0.8). The known group validity shows that both EQ-5D-5L and SF-6D can differentiate the patient's health status based on cataract surgery, visual acuity, and comorbidity. The Bland Altman plot shows the level of agreement between EQ-5D-5L and SF-6D of 91.7%. In better health status, the utility index of EQ-5D-5L is higher and vice versa, in the worse health status the utility index of SF-6D is higher. Conclusion: Both the EQ-5D-5L and SF-6D instruments are valid for assessing the utility index in cataract patients. By using different instruments, there are differences in the utility value of cataract patients based on their health status. Therefore it is necessary to consider in choosing the instrument in assessing utility as an outcome parameter in pharmacoeconomic study.