Approaches to Studying Determinants of Racial-Ethnic Disparities in Stroke and Its Sequelae

Abstract

Disparities are differences in health outcomes among groups that originate from sources including historically experienced social injustice and broadly defined environmental exposures. Large health disparities exist, defined by many factors including race/ethnicity, sex, age, geography, and socioeconomic status. Studying disparities relies on measures of disease burden. Traditional measures, such as mortality, may be less applicable to neurological disorders, which often lead to substantial morbidity and lower quality of life, without necessarily causing death. Measures such as disability-adjusted life-years or healthy life expectancy may be more appropriate for assessing neurological disease and permit comparisons across diseases and communities. There are many approaches that can be used to study disparities. Analyses of population-based observational studies, patient registries, and administrative data all contribute to the understanding of disparities in humans. Animal and other experimental designs, including clinical trials, may be used to identify mechanisms and strategies to reduce disparities. All of these approaches have strengths and weaknesses. Ultimately, understanding and mitigating disparities will require use of all of these methods. Crucially, a focus on not only improving outcomes among all individuals in society but minimizing or eliminating differences between those with better outcomes and those who have historically been disadvantaged should drive the ongoing investigations into disparities. This review is focused on epidemiological approaches to examining the depth and determinants of racial-ethnic disparities in the United States related to stroke, stroke care, and stroke outcomes.

Keywords: cerebrovascular disorders; cohort studies; epidemiology; health equity; quality of life; stroke.

Figure:. Distinguishing increased incidence from case-fatality as causes of disparities in stroke mortality

The figure illustrates the difference between increases in stroke incidence versus increases in stroke case-fatality as potential mechanisms for increased stroke mortality in Black populations compared to White populations, and implications for required remendies for mitigating the increase in mortality. The outer circles represent stroke incidence and the smaller shaded circles stroke mortality. Evidence shows (“Proven” box in figure; see text) that stroke incidence is increased in Black populations (larger outer circle on the right of the figure) with a proportional increase in mortality (the size of the inner circle). Another potential way in which increased mortality could occur (“Disproven” shaded box on the left of figure) would be to have stroke incidence remain the same for both populations (outer dashed circles), with an increase in proportional size of the mortality among the Black population (inner gray-shaded circle). Implications for required remedies to reduce disparities in mortality are provided in the dashed boxes.