Place of Birth Has Strong Influence on Stroke Risk
A new study published in the December issue of Neurology reports on the strong influence of birthplace on stroke risk. A person born in the “Stroke Belt" will continue to have a higher risk of stroke even if they have moved away.
M. Maria Glymour, ScD, of Harvard School of Public Health, and colleagues evaluated stroke mortality rates for United States–born black and white people aged 30–80 years for 1980, 1990, and 2000. This data was defined by birth state, state of adult residence, race, sex, and birth year.
Four “Stroke Belt” (SB) exposure categories were defined: born in a SB state (North Carolina, South Carolina, Georgia, Tennessee, Arkansas, Mississippi, or Alabama) and lived in the SB at adulthood; non-SB born but SB adult residence; SB-born but adult residence outside the SB; and did not live in the SB at birth or in adulthood (reference group).
The researchers findings noted an elevated stroke mortality associated with both SB birth and, independently, SB adult residence. The highest risk was found to be in persons who were born in the SB and continued to live there as an adult.
For African-Americans born in the Stroke Belt and living there as adults, the odds ratio for stroke mortality was 1.55 in 1980, 1.47 in 1990, and 1.34 in 2000. For white individual in the same group, the odds ratios were 1.45 in 1980, 1.29 in 1990, and 1.34 in 2000.
For reasons that have eluded explanation, residents of the southeastern U.S. historically have had a 20% to 50% greater risk of stroke mortality compared with residents living elsewhere in the country. This influence of residence in the Stroke Belt has little association with conventional stroke risk factors, social resources, or access to medical care.
Future studies of stroke risk should include detailed information about movement from one region to another. Such information might show whether people who move have different risk patterns help identify more precisely the point in life when stroke risk begins to increase. That information could aid the development of risk-reduction strategies specific to different regions of the country, the authors concluded.
Glymour MM, et al "Birth and adult residence in the Stroke Belt independently predict stroke mortality" Neurology. 2009; 73: 1858-65.