Abstract
BACKGROUND: Multidimensional health-related quality of life (HRQOL) instruments, such as the EQ-5D, are increasingly used to assess inequalities in health. However, it is necessary to explore the ability of these instruments to capture differences between population groups, especially in low/middle-income countries. This study aimed to investigate whether the EQ-5D-3L instrument can detect differences in HRQOL between groups of different socioeconomic status (SES) in Brazil. METHODS: Data collection occurred during the Brazilian EQ-5D-3L valuation study and included respondents aged 18 to 64 years enrolled in urban areas. SES was aggregated into three categories: "higher" (A and B), "intermediate" (C) and "lower" (D and E). EQ-5D-3L index was calculated considering the Brazilian value set. A mixed-effects regression model was estimated with random effects on individuals and marginal effects on SES, sex, and educational attainment. Odds ratios for the chance of reporting problems for each EQ-5D dimension were estimated by logistic regression. RESULTS: A total of 9,148 respondents were included in the study. Mean age was 37.80 ± 13.13 years, 47.4% were men and the majority was ranked as classes B or C (38.4% and 50.7%, respectively). Participants in lower SES classes reported increasingly poorer health compared to individuals in higher classes. The mean EQ-5D-3L index decreased as SES deteriorates being significantly higher for classes A and B (0.874 ± 0.14) compared to class C (0.842 ± 0.15) and classes D and E (0.804 ± 0.17) (p < 0.001). The same was observed for the mean EQ-VAS scores (84.0 ± 13.8 in classes A and B, 81.0 ± 17 in class C and 78.3 ± 18.7 in class C [p < 0.001]). The multivariate analysis confirmed that SES is an independent factor that effects EQ-5D-3L index measures. Participants in intermediate and lower SES classes have a statistically significant lower EQ-5D-3L index compared to participants in classes A and B, regardless of age, sex, and educational attainment. CONCLUSION: In a Brazilian population sample, the EQ-5D-3L instrument was able to detect important differences between groups with distinct socioeconomic statuses (SES). The EQ-5D-3L is useful for exploring inequities in health.