Leveraging Mediation Analysis as a Tool to Study Mechanisms Underlying Health Inequities.

Abstract

Purpose: To describe three statistical approaches that help gain a comprehensive understanding of mechanisms underlying health inequities: univariate regression analysis, effect modification analysis, and mediation analysis.

Methods: We described how univariate regression analysis, effect modification analysis, and mediation analysis can be used to gain insight into mechanisms underlying health inequities. We demonstrated the application of these approaches using a motivating example from the Health and Retirement Study in which we studied the role of education in ethnic disparities in episodic memory.

Results: Univariate regression analysis showed that Hispanic individuals on average had lower episodic memory scores compared to non-Hispanic individuals. Effect modification analysis showed that the beneficial effect of education on episodic memory was less strong in Hispanic individuals compared to non-Hispanic individuals. Mediation analysis showed that the ethnic disparity in episodic memory was not only driven by effect modification, but also by differences in the distribution of education years across ethnic groups.

Conclusion: The combined study of effect modification and mediation provides a comprehensive understanding of the mechanisms that cause and sustain health inequities. Insight into these mechanisms is crucial to determine targets for interventions and policies aimed at eliminating health inequities.