Advances in the Understanding of Social Determinants of Health in Stroke

Over the past decades, inequities in stroke have gained increasing attention. Social determinants of health (SDOH) - conditions in which people are born, grow, work, live, and age, and the wider set of forces and systems shaping the conditions of daily life – are known drivers of inequities. Yet, little is known about the impact of SDOH on stroke incidence, care, and outcomes. Understanding these relationships will be helpful in designing interventions to address inequities. The purpose of this review is to summarize manuscripts published from 2022 through 2023 on the impact of SDOH on stroke.

Three commissioned manuscripts focused on SDOH and neurological disease. The American Heart Association Scientific Statement “Strategies to Reduce Racial and Ethnic Inequities in Stroke Preparedness, Care, Recovery, and Risk Factor Control” summarized intervention studies addressing racial and ethnic inequities in stroke care and outcomes¹. The SDOH subgroup of the National Advisory Neurological Disorders and Stroke Council Working Group for Health Disparities and Inequities in Neurological Disorders published an article delineating key considerations for SDOH in neurological disease, outlining recent interventions, knowledge gaps, and recommendations to address SDOH². Finally, the article “Determinants of Inequities in Neurologic Disease, Health, and Well-being: The NINDS Social Determinants of Health Framework” illustrated a model for conceptualizing the impact of SDOH on inequities in neurological disease (Figure 1)³. This model, adapted from three sources - the World Health Organization Commission on SDOH⁴, the Schulz et al. model⁵, and the work of Williams et al.⁶ - shows the interplay between upstream structural determinants (cultural and social values; structural racism; economic, public and social policies); social status determinants (socioeconomic position, class, education, occupation, and income): intermediate factors (public health and healthcare, built environment, sociocultural environment); intrapersonal determinants (health behaviors and knowledge, psychosocial factors, disability); biological determinants, and inequities in neurological health.

Figure 1.

The National Institute of Neurological Disorders and Stroke SDOH Framework for Addressing Health Disparities. Reproduced from Griffith DM, et. al, Neurology, 2023³ (reprinted with permission).

With regards to structural determinants of health (Figure 1), several recent studies focused on the impact of immigration on stroke risk and care. Studies utilizing administrative data in Canada found that stroke incidence followed a J-shaped curve between the proportion life spent in Canada and stroke incidence and disability; it was highest among immigrants who had either immigrated at an early age or immigrated recently⁷, and that the attributable cost of stroke among immigrants was significantly higher than among non-immigrants⁸. Registry data in Denmark suggested that immigrants had greater pre-hospital delays compared to their non-immigrant counterparts⁹. Furthermore, immigrants were less likely to receive acute reperfusion therapies even when adjusting for time to presentation, and had lower odds of stroke unit admission, dysphagia screening, and early rehabilitation services than non-immigrants¹⁰. An analysis of administrative data in the United States (US) showed that compared with US-born Black individuals, all-cause and cardiovascular mortality rates were lower among Black individuals born in Africa, the Caribbean, South America, and Central America, but stroke-specific mortality rates were similar¹¹.

Neighborhood, zip code, and other related location-specific measures (largely shaped by discriminatory policies) are increasingly recognized as important structural determinants of health. Living in a low-income neighborhood was found to be an important determinant of hypertension severity in intracerebral hemorrhage survivors and partially explained the excess likelihood of uncontrolled blood pressures among Black vs. White people in a primary prevention setting^12,13. The area deprivation index, a validated measure of community-level socioeconomic deprivation, was associated with greater stroke severity, infarct volume, and 30-day mortality after stroke^14,15. A related study demonstrated that socially disadvantaged US counties had significantly higher stroke mortality than counties with low area-level social deprivation¹⁶. Similarly, historical redlining was associated with modern-day stroke prevalence in New York City independently of contemporary individual measures of socioeconomic status¹⁷. Data from the Black Women’s Health Study suggested that Black women who experienced interpersonal racism had higher stroke incidence than those without prior experiences of racism¹⁸, thus establishing a direct link between interpersonal racism and stroke incidence later in life.

Social status determinants of health (Figure 1) were shown to have an impact on stroke prevalence and care. Low education, low income, and living in a health care professionals shortage area were associated with increased community-level stroke prevalence in a cross-sectional study of residents in New York City¹⁷ and were critical drivers of the excess likelihood of uncontrolled blood pressure among Black vs. White participants in the REGARDS study¹³. Unemployed and low-income stroke patients had lower likelihood of receiving reperfusion therapies, even when only considering patients with timely hospital arrival¹⁹. When using composite measures of SES, incorporating information on education, income, and occupation, low SES was associated with worse long-term recovery of upper limb motor function²⁰, increased death and functional dependency at 3 months²¹, and greater decline in health-related quality of life up to 10 years after stroke²². An analysis from the National Health and Nutrition Examination Survey demonstrated that the prevalence of food insecurity among stroke survivors was higher than among those without prior history of stroke, and low education and income were associated with higher likelihood of facing food insecurity after stroke²³.

In the past two years, although our understanding of the impact of SDOH on stroke has expanded, numerous gaps remain. First, it is critical to understand how each SDOH individually and in combination affects stroke prevalence, care, and outcomes. Second, more research is needed to determine which individual-level, place-level, or policy interventions are efficacious in addressing stroke inequities². Prior research in other areas suggest that community engaged, multi-level, interdisciplinary interventions are likely to address inequities¹. Additionally, addressing more structural and social status determinants will likely have a larger impact than interventions geared towards individual health literacy and behavior change^1,3. Once efficacious interventions are identified, it will be necessary to evaluate effectiveness, implementation, and dissemination.

Non-standard Abbreviations and Acronyms

SDOH

Social determinants of health

US

United States