Changes in socioeconomic inequality in self-assessed health in South Africa: The contributions of changes in inequalities between and within socioeconomic groups.

Globally, poor health is associated with lower socioeconomic status (i.e., the gradient). While significant socio-demographic drivers of socioeconomic inequalities have been documented in South Africa, little is known about changes in socioeconomic inequalities in health between and within socioeconomic groups, an essential consideration for closing the gaps between socioeconomic groups. This paper assesses changes in health inequalities in South Africa, using self-assessed health (SAH) to uncover the relative contributions of inequalities between and within socioeconomic groups to changes in socioeconomic inequalities in SAH. It uses data from five waves (2008, 2010/11, 2012, 2014/15, and 2017) of South Africa's nationally representative National Income Dynamics Study (NIDS) as cross-sectional with a final sample size ranging between 13,732 and 21,303 adults (>18 years). Based on five categories, SAH was recategorised and dichotomised as "good health" with SAH = 1. Socioeconomic status and quintiles were based on per capita household expenditure. The standard concentration index measured socioeconomic inequality in SAH. A recent methodology decomposes changes in the concentration index of SAH into changes in inequality within and between socioeconomic groups. A pro-poor shift or change is when socioeconomic inequality in health (including for between- and within-socioeconomic groups) reduces between two time periods, while an increase in inequalities means a pro-rich shift or change. The results show a significant pro-rich gradient in SAH among adults in South Africa (concentration index ranging between 0.0053 and 0.0327), with good health reported more by relatively wealthier adults than their more socioeconomically deprived counterparts. This pro-rich gradient declined overall between 2008 and 2017 (a pro-poor shift), associated mainly (between 96% and 100%) with reduced inequalities between socioeconomic groups, i.e., closing gaps between socioeconomic groups. Addressing health inequalities in South Africa requires a multisectoral approach prioritising socioeconomically deprived individuals and policy to reduce health disparities between groups that leave no one behind.