The shifting stroke belt. Changes in the geographic pattern of stroke mortality in the United States, 1962 to 1988

Abstract

Background and purpose: The factors that contribute to the Stroke Belt--a concentration of high stroke mortality rates in the southeastern United States--remain unidentified. Previous hypotheses that focused on physical properties of the area have not been confirmed. This study describes changes in the locations of areas with the highest rates of stroke mortality and the implications for new hypotheses regarding the Stroke Belt.

Methods: We calculated annual, age-adjusted stroke mortality rates for black women, black men, white women, and white men for the years 1962 to 1988 using a three-piece log-linear regression model. Maps were produced with the state economic area (SEA) as the unit of analysis. The baseline Stroke Belt was defined as the area with the largest concentration of high-quintile SEAs in 1962.

Results: The concentration of high-rate SEAs tended to shift away from the Piedmont region of the Southeast and toward the Mississippi River valley. For example, whereas among black women in 1962, 72% of SEAs in the baseline Stroke Belt were in the highest quintile, by 1988 this percentage had dropped to 48%. Similar patterns were observed for the other race/sex groups.

Conclusions: Temporal changes in the location of areas with the highest stroke mortality rates suggest that new hypotheses for understanding the geographic pattern of stroke mortality should consider temporal trends in a variety of medical, socioeconomic, and behavioral factors.