Impact of nativity and race on "stroke belt" mortality

The southeastern region of the United States has been recognized for 6 deca des as an area of excess cerebrovascular mortality rates. While the reasons for the disease variation remain an enigma, South Carolina has consistentl y been the forerunner of the "Stroke Belt." To determine the effects of nat ivity (birthplace) on stroke mortality rates in South Carolina, proportiona l mortality ratios (PMRs) were calculated for stroke deaths in South Caroli na during 1980-1996 according to birthplace and stratified by gender, race, age, and educational status. The analyses revealed a graded risk of stroke by birthplace, with the highest PMRs (95% CI) among individuals born in So uth Carolina (104.8 [103.4 to 106.3]), intermediate PMRs in those born in t he Southeast other than South Carolina (92.5 [90.2 to 94.9]), and lowest PM Rs for those born outside the Southeast (77.4 [74.9 to 80.1]). The lower st roke PMRs for individuals born outside the Southeast were more striking in blacks (51.8 [45.2 to 59.3]) than in whites (84.9 [82.0 to 88.0]) and for m en (73.3 [69.5 to 77.3]) than women (83.5 [79.9 to 87.3]). The findings, pa rticularly in blacks, were not explainable by gender, differences in age, a nd/or markers of educational and socioeconomic status. These findings sugge st that nativity is a significant risk marker for the geographic variation in stroke mortality. Moreover, the regional disparities for nativity and su bsequent stroke mortality appear to be greater in blacks than in whites and for men than for women. An understanding of factors linking birthplace to risk for cerebrovascular mortality could facilitate efforts directed at str oke prevention.