A system that rewards population health must be able to measure and track health inequalities. Health inequalities have most commonly been measured in a bivariate fashion, as a joint distribution of health and another attribute such as income, education, or race/ethnicity. The author of this article argues that this practice gives insufficient information to reduce health inequalities and proposes a summary measure of health inequalities, which gives information both on overall health inequality and bivariate health inequalities. Asada introduces two approaches to develop a summary measure of health inequalities.
After describing the two approaches in terms of building-block measurement properties, aggregation, value, data and sample size requirements, and communication, Asada recommends that, when data are available, a summary measure should use the top-down approach. In addition, a strong communication strategy is necessary to allow users of the summary measure to understand how it was calculated and what it means.