Exposure to the US Stroke Buckle as a risk factor for cerebrovascular mortality.

BACKGROUND For decades, the Stroke Buckle region in the southeastern USA has had a high incidence of deaths from cerebrovascular disease relative to the rest of the country. We test here the possibility that temporary exposure to the Stroke Buckle can explain some of the excessive stroke mortality there. METHODS We examined all US death records between 1979 and 1988, noting whether individuals died inside or outside the 153-county Stroke Buckle in the coastal plains of North Carolina, South Carolina and Georgia. We also noted the decedents' county of residence, which was coded separately. Proportionate mortality ratios (PMRs) were used to assess the risk of dying of a stroke. RESULTS Stroke Buckle residents who died in their home county were at an increased risk of dying of a stroke (PMR = 130.2; 95% confidence interval, CI = 128.9-131.6; p < 0.0001). Visitors to the Buckle were also at an increased risk of dying of a stroke (PMR = 111.9; 95% CI = 107.5-116.2; p < 0.0001), and Buckle residents who died while outside of the region were less likely to die of a stroke (PMR = 89.9; 95% CI = 86.2-93.6; p < 0.0001). CONCLUSIONS These results show that even short-term exposure to the Stroke Buckle accounts for some of the elevation in stroke deaths there.