Unequal utilization in healthcare can potentially affect the right to health. Access to healthcare services and achieving positive health outcomes and health equity are essential principles in promoting human rights. This study aims to assess and analyze socioeconomic-related inequalities in outpatient health services utilization (OHSU) among various socio-demographic subgroups to inform policies that foster health equity. Data were collected through a cross-sectional survey of 1200 households in Tehran, Iran. Inequality in OHSU among the socio-demographic subgroups was calculated by concentration, Wagstaff, and Erigers indices. Decomposition was used to identify the factors contributing to inequality in OHSU. Marginal effect and elasticity were used to calculate the relative absolute shares of socio-demographic variables in the inequality. The rate of OHSU was 63.61% (CI: 60-66.80) which concentrated among households with better socioeconomic status. Based on the results, living in an affluent neighborhood (Relative share (RS): 85.48) and having a disabled member in the household (RS: 6.58) were the most important factors in the concentration of OHSU in favor of the privileged groups. In contrast, very low levels of health knowledge (RS: -83.79) and having basic insurance coverage (RS: -3.92) concentrated OHSU in favor of the lower socioeconomic households. The study was conducted based on survey data, and this may lead to some limitations. Given that this study was a cross-sectional study, we were unable to establish causal relationships between explanatory variables and outpatient health service utilization and its relevant predictors. Households with disabled member(s), as well as a member(s) with chronic diseases, may experience severe inequalities in access to healthcare services. Policies that facilitate access to health services for these households can play a significant role in improving health equity.
Keywords: decomposition; health services utilization; inequality; outpatient healthcare; socioeconomic status.