Smoking More Than Doubles Risk of Stroke in African Americans

While the impact of smoking on cardiovascular health is well-documented, new research suggests the impact of smoking on the risk of stroke in African Americans may be a more serious issue than previously anticipated.

Results of the study, which was an analysis of data from the Jackson Heart Study, indicated current smokers were at more than double the risk of experiencing a stroke event, with those smoking 20 or more per day were at 2.8 times greater risk of having a stroke than nonsmokers.

"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 investigator Adebamike Oshunbade, MD, MPH, post-doctoral research fellow at the University of Mississippi Medical Center in Jackson, Mississippi and a fellow of the American Heart Association (AHA) Tobacco Regulation and Addiction Center, in a statement from the AHA.

Using data from the Jackson Heart Study, which is the largest US study assessing cardiovascular risk factors among African Americans, investigators sought to further investigate the relationship between cigarette smoking and stroke incidence. Using this information, investigators identified a cohort of 4410 patients for inclusion in the National Institutes of Health (NIH)-funded study.

The original Jackson Heart Study cohort contained 5306 patients between the ages of 21-84 years from the tricounty area surrounding Jackson, MS. Investigators excluded 896 participants based on a history of stroke or cardiovascular disease or missing information.

Participants within the Jackson Heart Study were classified as current smokers, never smokers, and past smokers. In addition to current smoking status, the protocol of the original study assessed the number of cigarettes smoked per day, which was referred to as smoking intensity and also used to calculate smoking burden as pack-years.

For the purpose of analysis, investigators compared the rates of stroke incidence through 2015 among current smokers, never smokers, and past smokers. Additional analyses evaluated the impact of stroke incidence based on the number of cigarettes smoked per day.

In total, 781 participants were past smokers, 546 were current smokers, and 3083 were never smokers. During the follow-up period, which lasted a median of 11.8 years, a stroke event occurred in 183 participants.

After adjusting for cardiovascular risk factors, the investigators’ analysis indicated risk of stroke in current smokers was significantly higher than never smokers (HR, 2.48; 95% CI, 1.60-3.83), but no significant difference between past smokers and never smokers (HR, 1.10; 95% CI, 0.74-1.64). When examining impact of smoking burden, those smoking 1-19 cigarettes per day (HR, 2.28; 95% CI, 1.38-3.86) had a lower incidence of stroke than those smoking 20 or more cigarettes per day (HR, 2.78; 95% CI, 1.47-5.28).

"This study provides further strong evidence of the link between cigarette smoking and stroke in African Americans," said David Goff, MD, PhD, director of the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute, in a statement from the NIH. "We know that quitting smoking is one way to lower the risk for stroke, which is particularly important for the most vulnerable populations during this pandemic."

This study, “Cigarette Smoking and Incident Stroke in Blacks of the Jackson Heart Study,” was published in the Journal of the American Heart Association.