Distal, intermediate, and proximal mediators of racial disparities in renal disease mortality in the United States

Abstract

In the United States, racial disparities in mortality due to renal disease are due to distal (socioeconomics), intermediate (hypertension and diabetes), and proximal (health behaviors) factors. Thus, elimination of racial disparities in renal disease mortality in this country requires a wide range of policies and programs that enhance income, promote behaviors, and prevent medical conditions such as hypertension and diabetes. Please cite this paper as: Assari S. Distal, intermediate, and proximal mediators of racial disparities in renal disease mortality in the United States. Background: Kidney failure and associated mortality is one of the major components of racial disparities in the United States. Objectives: The current study aimed to investigate the role of distal (socioeconomic status, SES), intermediate (chronic medical diseases), and proximal (health behaviors) factors that may explain Black-White disparities in mortality due to renal diseases. Patients and Methods: This is a nationally representative prospective cohort with 25 years of follow up. Data came from the Americans' Changing Lives (ACL) study, 1986 to 2011. The study included 3361 Black (n = 1156) or White (n = 2205) adults who were followed for up to 25 years. Race was the main predictor and death due to renal disease was the outcome. SES, chronic medical disease (diabetes, hypertension, obesity), and health behaviors (smoking, drinking, and exercise) at baseline were potential mediators. We used Cox proportional hazards models for data analysis. Results: In age and gender adjusted models, Blacks had higher risk of death due to renal disease over the follow up period. Separate models suggested that SES, health behaviors and chronic medical disease fully explained the effect of race on renal disease mortality. Conclusions: Black-White disparities in rate of death due to renal diseases in the United States are not genuine but secondary to racial differences in income, health behaviors, hypertension, and diabetes. As distal, intermediate, and proximal factors contribute to racial disparities in renal disease mortality, elimination of such disparities requires a wide range of policies and programs that target income, medical conditions, and health behaviors.