1. Current smoking was found to be associated with and increased risk of stroke among blacks in a dose-dependent relationship.
2. Former smokers did not appear to be at an increased risk of stroke when compared with non-smokers, suggesting a reduction in stroke incidence associated with smoking cessation.
Evidence Rating Level: 2 (Good)
Stroke is a leading cause of morbidity and mortality in the United States, and smoking is known to be an independent, modifiable risk factor for development of stroke. Blacks are substantially more likely to develop, and die from, a stroke when compared with other racial groups. To address the limited data regarding cigarette smoking and incident stoke in blacks, this prospective cohort study utilized participants of the Jackson Heart Study, the largest, single-site prospective cohort study designed to examine risk factors for heart disease in blacks. A total of 4,410 participants were included, representing 83.1% of the original cohort. In addition to stroke incidence, the investigators measured carotid intimal medial thickness (CIMT), a marker of atherosclerosis that has been correlated with the incidence of stroke. A total of 3,083 participants (M [SD] age = 53.1 [13.0] years, 30% male) identified as never having smoked, 781 (M [SD] age = 59.2 [11.2] years, 47% male) as former smokers, and 546 (M [SD] age = 51.6 [11.1] years, 51% male) as current smokers. During follow-up, 183 participants developed stoke. Compared with non-smokers, current smokers were found to be at an increased risk of stroke (HR 2.57, 95% CI 1.75 to 3.79), whereas the risk of stroke was not different among former smokers (HR 1.16, 95% CI 0.81 to 1.68). A dose-dependent risk of stroke was seen in current smokers who reported using between 1 and 19 cigarettes daily (HR 2.28, 95% CI 1.38 to 3.86) and those who reported using greater than 20 cigarettes daily (HR 2.78, 95% CI 1.47 to 5.28). CIMT was increased in both current and former smokers when compared with non-smokers after adjusting for age and sex. Similar to the previous findings, a significant, dose-dependent increase in CIMT was seen in participants smoking 1 to 19 cigarettes daily (β coefficient 0.05, 95% CI 0.0 to 0.1, p = 0.02) and in participants smoking greater than 20 cigarettes daily (β coefficient 0.08, 95% CI 0.02 to 0.14, p = 0.008) when compared with non-smokers. This study highlights the increased risk of stoke associated with smoking among blacks and emphasizes the need for targeted public health interventions to modify this risk. It also suggests that smoking cessation has a role in reducing incident stroke among blacks.
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