From Rich to Poor: A Decomposition Analysis of Socioeconomic Inequality in Health-related Quality of Life in Iran.

Objectives: Socioeconomic status (SES) is a well-established predictor of health outcomes across an individual's lifespan. People from lower socioeconomic backgrounds generally have shorter life expectancies and lower levels of health-related quality of life (HRQoL) compared with those from higher-income groups. This study aimed to quantify income-related inequalities in HRQoL among adults in Iran.

Methods: A total of 3518 adults aged 18 years and older were selected using a convenience sampling method across 9 provinces in Iran. HRQoL was assessed with the EuroQoL 5-Dimension 5-Level (EQ-5D-5L) instrument, which evaluates 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The concentration index (CI) approach was used to measure income-related inequality in worse HRQoL (disutility=1-utility value) and to identify the socioeconomic factors contributing to the observed inequality.

Results: The CI for worse HRQoL was -0.116, while the CI for the EuroQol visual analogue scale (EQ-VAS) score was 0.027. The CIs for reporting any problems in the EQ-5D-5L dimensions were: mobility (-0.122), self-care (-0.070), usual activities (-0.074), pain/discomfort (-0.139), and anxiety/depression (-0.139). Decomposition analysis showed that income (38.00%), educational level (31.53%), age (8.05%), and physical activity (7.30%) were the main factors contributing to socioeconomic inequality in poorer HRQoL in Iran.

Conclusions: This study identified a pro-poor distribution of poorer HRQoL and reported problems across all dimensions of the EQ-5D-5L in Iran. Targeted interventions should focus on reducing disparities in income, education, and physical activity levels.