Ancel Keys Lecture: Adventures (and misadventures) in understanding (and reducing) disparities in stroke mortality

Abstract

Background and Purpose: Racial and geographic disparities in stroke mortality have been documented for over 50 years, and for those aged 45 to 64 are among the largest for any disease. The causes of the disparities have been mysterious; however, investments by NINDS, NHLBI and CDC are now providing insights into the causes.

Methods: Complementary study designs provide information on different aspects of the disparities. Vital statistics data track temporal patterns in stroke mortality, an objective index of the success in overcoming the disparities. Surveillance studies assess of the contributions of incidence versus case fatality to the disparities, a distinction critical to guide efforts to reduce the disparities. Finally, cohort studies give insights to the contribution of specific risk factors to disparities in either incidence or case fatality, allowing targeted interventions.

Results: While deaths from stroke mortality declined by a third in the most recent eleven years, there has been a 35% increase in the black-white disparity and little change in geographic disparities. Surveillance studies suggest that the black-white disparity is primarily attributable to differences in incidence, and also have potentially unmasked Hispanic-white differences in incidence that are not apparent in mortality trends. Longitudinal cohort studies are suggesting multiple targets for intervention such as a multi-dimensional impact of blood pressure on the black-white differences.

Conclusion: After suffering these disparities over a half-century, information is now emerging to allow us to better understand the underpinnings of the disparities and potentially enter a new era of targeted interventions to reduce these disparities.

Keywords: geography; mortality; race; rural health; stroke; urban health.

Figure 1

Race/ethnic differences in deaths from cerebrovascular disease (ICD 10: I60 – I69) for US residents aged 45 and above. Figure 1A (left) shows the age-adjusted (year 2000 standard) death rate per 100,000 for mutually exclusive race/ethnic strata: non-Hispanic whites (White), non-Hispanic blacks (Black), Hispanic (all races), non-Hispanic Native American/Alaska Natives (Native American), and non- Hispanic Asians (Asian). Figure 1B (right) shows the cerebrovascular disease mortality ratio for minority groups relative to non-Hispanic whites.

Figure 2

Urban-rural differences in deaths from cerebrovascular disease (ICD 10: I60 – I69) for US non- Hispanic white residents aged 45 and above. Figure 2A (left) shows the age-adjusted (year 2000 standard) death rate per 100,000 by the NCHS Urban-Rural Classification Scheme for counties classified as large central metro (most urban), large fringe metro, medium metro, small metro, micropolitan, or non-core (most rural). Figure 2B (right) shows the cerebrovascular disease mortality ratio for urbanrural groups relative to large central metro.

Figure 3

Stroke Belt versus non-Stroke Belt differences in deaths from cerebrovascular disease (ICD 10: I60 – I69) for non-Hispanic white US residents aged 45 and above. Figure 3A (left) shows the ageadjusted (year 2000 standard) death rate per 100,000 by the REGARDS defined stroke belt (states of North Carolina, South Carolina, Georgia, Tennessee, Alabama, Mississippi, Arkansas and Louisiana) and non-stroke belt regions (all states not included in the stroke belt). Figure 3B (right) shows the cerebrovascular disease mortality ratio for the stroke belt relative to the non-stroke belt.