Csilla Manoczki, MD
Studies have suggested that stroke disparities may be explained by other risk factors, such as social determinants of health (SDOH), beyond the traditional Framingham Stroke Risk Profile. According to the WHO: “the social determinants of health are mostly responsible for health inequities – the unfair and avoidable differences in health status seen within and between countries”. This study investigated the association between incident stroke and the increasing number of multiple SDOH in the individual.
Data was used from the REGARDS study, a population-based prospective cohort study designed to identify the mechanisms of higher stroke mortality observed in the southeastern United States and among the Black population. The analytic sample of this study included 27813 individuals. Mean age at baseline was 64.7 years; 55.4% were women; 40.4% were of Black race; and 83.4% of all participants were <75 years old. Those with reported history of stroke at baseline were excluded. The primary outcome of the study was incident stroke based on expert adjudication following review of medical records.
Based on the major categories described in the Healthy People 2020 framework, 10 SDOH were selected. Seven out of these were associated with stroke, which were retained for further analysis (race, education, income, zip code poverty, health insurance, social isolation, residence in one of the 10 lowest ranked states for public health infrastructure).
Outcomes were as follows:
- The number of incident strokes was 1470 over median follow up period of 9.5 years.
- Stroke incidence was lower in the younger (<75 years) vs the older (≥75years) cohort.
- In the younger cohort, the incidence of stroke increased with each additional SDOH. When compared with individuals without SDOH, the hazard ratio (HR) for stroke incidence was 1.44 (95% CI, 1.07–1.78), 1.82 (95% CI, 1.48–2.24), and 2.38 (95% CI, 1.94–2.92) for those with 1,2, and ≥3 SDOH, respectively. The association remained significant in the fully adjusted analysis taking multiple individual covariates into account, including traditional stroke risk factors.
- In the older cohort, there was no significant effect observed on stroke incidence with increasing number of SDOH in the fully adjusted analysis.
- Those with a greater number of SDOH were more likely to be women and of Black ethnicity, have low annual income, reside in areas with high poverty rate and poor public health infrastructure, and have a history of diabetes mellitus and hypertension.
This study provides further evidence on the marked compound effect of various factors of socio-economic status on health outcomes, as observed for first incident stroke in those under 75 years of age. In vulnerable demographic groups, a tailored approach is suggested with augmented interventions to reduce socioeconomic inequalities, alongside maximizing traditional risk factor control and promoting positive health behavior.