Dr Adebamike OshunbadeAdebamike Oshunbade, MD, MPH
New study data suggest that cigarette smoking was associated with a dose-dependent higher risk of all stroke in black individuals, though past smokers did not have a significantly increased risk of all stroke compared with those who never smoked.1

All told, the stroke risk was 2.5 times higher for those who currently smoked compared to non-smokers (hazard ratio [HR], 2.48; 95% CI, 1.60–3.83), while the risk difference between past and never smokers (HR, 1.10; 95% CI, 0.74 1.64) was not significant. The dose-dependent increases in the risk of stroke from smoking intensity were noted as 2.3 times (HR, 2.28 95% CI, 1.38–3.86) and 2.8 times (HR, 2.78; 95% CI, 1.47–5.28) greater for those who were smoking 1 to 19 cigarettes per day and ≥20 cigarettes per day, respectively.

“Smoking increases the risk of developing stroke among African Americans, and that risk becomes higher as the number of cigarettes smoked per day increases. The more you smoke, the more you stroke,” said lead author Adebamike Oshunbade, MD, MPH, post-doctoral research fellow, University of Mississippi Medical Center, and fellow, American Heart Association Tobacco Regulation and Addiction Center, in a statement.2

This study population consisted of 5306 participants aged 21 to 84 years who were recruited from the tri-county area surrounding Jackson, Mississippi. They were evaluated at baseline from 2000 to 2004 and completed a pair of subsequent follow-up visits in 2005 to 2008, and 2009 to 2013. The final analysis included current smokers (n = 546), past smokers (n = 781), and non-smokers (n = 3083).
 
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Of the full population, a total of 183 participants experienced strokes (current smokers: n = 37 [6.8%]; past smokers: n = 41 [5.2%]; nonsmokers: n = 105 [3.4%]). Of the 366 participants smoking 1 to 19 cigarettes per day, 24 experienced stroke (6.6%), whereas 13 (7.2%) of the 180 participants who smoked ≥20 cigarettes experienced stroke. For both past and current smokers, the higher incidence of stroke compared with never smokers was significant (P = .0001).

“We also assessed the extent of fatty plaque build-up in the carotid arteries of African American smokers by a non-invasive procedure called carotid intima-media thickness. We found an accelerated build-up of fatty plaques in some of the major blood vessels of the brains of smokers, which could play a role in the development of stroke among African Americans,” Oshunbade said.

Adjustment for C-reactive protein (CRP) minimally attenuated the increased risk of stroke in current smokers compared with never smokers (HR, 2.11; 95% CI, 1.38–3.22). Additionally, current smokers smoking 1 to 19 cigarettes per day had higher carotid intima-media thickness (CIMT) compared with never smokers (β, 0.05; P = .02), and those currently smoking ≥20 cigarettes/day also had higher CIMT compared with never smokers (β, 0.08; = .008).

Further adjustment for a number of factors (age, sex, education level, body mass index, diabetes mellitus, systolic blood pressure, hypertension, total cholesterol, fasting triglycerides, physical activity, and statin use) was also linked with increased CIMT compared with never smokers. Current smokers using ≥20 cigarettes/day had higher CIMT compared with never smokers (β, 0.12; P <.001), but the association between CIMT and smoking 1 to 19 cigarettes/day among current smokers was no longer significant.

Oshunbade and colleagues wrote that the results should strengthen calls to action for African Americans, public health officials, and the tobacco industry. “Our findings support public health initiatives directed toward smoking cessation, especially among vulnerable groups like African Americans. This is particularly important because these populations have been targeted by tobacco companies,” he said.

“More public enlightenment campaigns should be geared toward warning African Americans about the modifiable risk of developing stroke from cigarette smoking,” Oshunbade concluded.
REFERENCES
1. Oshunbade AA, Yimer WK, Valle KA, et al. Cigarette Smoking and Incident Stroke in Blacks of the Jackson Heart Study. J Am Heart Assoc. 2020;9:e014990. doi: 10.1161/JAHA.119.014990
2. Risk of stroke may more than double for African Americans who smoke [press release]. Dallas, TX: American Heart Association; Published June 10, 2020. Accessed June 10, 2020. newsroom.heart.org/news/risk-of-stroke-may-more-than-double-for-african-americans-who-smoke