Validity of EQ-5D-5L health-related quality of life questionnaire in self-reported diabetes: evidence from a general population survey

Abstract

Background: This study aimed to assess the validity of the EQ-5D-5L in respondents with self-reported diabetes coming from a representative general population survey. Methods: 2974 respondents from the general adult population of Poland, chosen with multi-stage random sampling, were surveyed with HRQoL instruments (EQ-5D-5L, EQ VAS, SF-12, EQ-5D-3L) and a screening question about diabetes. To obtain EQ-5D index values, we used country-specific Polish value sets. We compared the instruments in terms of the ceiling effect, discriminatory power and frequency of individual health states. We evaluated construct validity in terms of known-groups validity and convergent validity of EQ-5D-5L dimensions and index values with other HRQoL measures. Results: In respondents with diabetes (n = 247), the percentage reporting 'no problems' with EQ-5D-3L was reduced by 34.5% with the use of EQ-5D-5L (from 14.2% to 9.3%, respectively). A significant improvement in informativity was noticed in mobility and pain/discomfort dimensions (a relative increase of 23.1% and 22.7%, respectively). Known-groups construct validity analysis confirmed prior hypotheses—index scores were higher in the following groups: younger respondents, males, those taking no medication or oral antidiabetic drugs, and respondents with higher levels of education. The convergence between related EQ-5D-5L and EQ-5D-3L or SF-6D dimensions was stronger than between unrelated dimensions. The Bland–Altman analysis showed a mean difference between EQ-5D-5L and EQ-5D-3L, SF-6D, EQ VAS/100 index scores of 0.047, 0.165 and 0.231 respectively. Conclusions: Our results support the validity of the EQ-5D-5L descriptive system and EQ-5D-5L index, based on the directly measured value set in respondents with self-reported diabetes coming from the general population.