Understanding the relationship between perceived discrimination, allostatic load, and all-cause mortality in US older adults: A mediation analysis.

OBJECTIVE: To understand the relationship between perceived discrimination, allostatic load, and all-cause mortality; and to determine whether allostatic load is a mediator in the relationship between perceived discrimination and all-cause mortality among an older adult US population.

METHODS: Data from the Health and Retirement Study (2006-2012) was analyzed. Cox proportional hazard models were used to investigate the relationship between all-cause mortality and perceived discrimination, and all-cause mortality and allostatic load. Linear regression models were used to investigate the relationship between perceived discrimination and allostatic load. A mediation model with perceived discrimination and allostatic loads as independent variables was used to determine the association with all-cause mortality.

RESULTS: There were 5062 adults over the age of 50 included in the analysis. The relationship between perceived discrimination and allostatic load was statistically significant (b:0.14, [95%CI 0.10,0.19]; p < 0.001). The relationship between perceived discrimination and all-cause mortality was statistically significant (HR: 1.12, [95%CI 1.03,1.22]; p = 0.01). The relationship between allostatic load and all-cause mortality was statistically significant (HR: 1.11, [95%CI 1.08,1.13]; p < 0.001). The mediation model resulted in a decrease in hazard ratio and loss of statistical significance for perceived discrimination (HR: 1.09, [95%CI 0.98,1.21]; p = 0.13) when allostatic load (HR: 1.17, [95%CI 1.10,1.24]; p < 0.001) was added to the Cox regression model, indicating full mediation.

CONCLUSIONS: Allostatic load fully mediates the relationship between perceived discrimination and all-cause mortality. Understanding the role of allostatic load in this relationship provides an additional implication for screening and indications for tighter control of the modifiable components of allostatic load by healthcare providers, especially among individuals who experience discrimination.