Risk increases as more cigarettes are smoked

According to the Office of Minority Health of the Health and Human Services Administration, African Americans are 50% more likely to have a stroke than their white counterparts and black men are 60% more likely to die from a stroke than whites.

Researchers with the Jackson Heart Study say that cigarettes are one likely contributor to those sobering statistics. Analysis of data collected over 10 years from 5,306 participants in the observational cohort study found that compared to African Americans who never smoked, current African-American smokers were almost two and half times more likely to have a stroke (HR, 2.48; 95% CI 1.60-3.83), wrote Adebamike Oshunbade, MD, MPH, of the University of Mississippi Medical Center in Jackson, and colleagues in the open access Journal of the American Heart Association. Moreover, the stroke risk appears to be dose-dependent, “(HR, 2.28 [95% CI, 1.38-3.86] and HR, 2.78 [95% CI, 1.47-5.28] for current smokers smoking 1-19 and ≥20 cigarettes/day, respectively),” they added.

In a prepared statement, Oshunbade said the study 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.”

The study recruited 5,306 African Americans, all of whom lived in three counties surrounding Jackson, ranging in age from 21 to 84. Of the total recruits, those with a history of stroke (n-232), missing stroke data (n=170), history of cardiovascular disease (n=340), missing smoking date (n=47) , and missing covariates (n=107) were not included in the final sample size of 4,410.

The final sample included 546 current smokers, 781 past smokers and 3,083 never smokers. In general, current smokers were younger than past smokers or never smokers (mean ages 51.6, 59.2, and 53.1, respectively P <0.001 for all). More than half of the current smokers were men (51%) versus 47% of past smokers and 30% of never smokers (P <0.001 for all). The health status of current smokers was more likely to be poor, and current smokers were more likely to regularly consume alcohol (73%) than past smokers (49%) or never smokers (42%). Of note, many current smokers did not pick up the habit until they reached their late teenage years (mean age 19.8).

“Participants were evaluated at baseline from 2000 to 2004 (visit 1) and completed 2 subsequent study follow‐up visits (visit 2, 2005–2008; visit 3, 2009–2013),” the JHS investigators wrote.

Smoking status was established during the baseline visit, as was hypertension and carotid intima-media thickness (CIMT).

Among the findings, over a median foll0w-up of 11.8 years:

  • “183 participants developed stroke (incidence rate, 3.49/1000 person‐years).
  • “Both past and current smokers had a higher incidence of stroke compared with never smokers (log‐rank P=0.0001).
  • “Among current smokers using 1 to 19 cigarettes/day, there were 24 stroke events.
  • “Current smokers using ≥20 cigarettes/day had 13 stroke events.”

When the findings were analyzed by gender, men who smoked had a higher stroke incidence rate than women who smoked. Of note, the “risk of stroke was not different in past smokers compared with never smokers (HR, 1.16; 95% CI, 0.81-1.68),” they wrote. But current and past smokers had increased CIMT compared to never smokers.

The researchers noted a number of limitations, including the fact that the sample was drawn from a single geographic area and the reliance on self-reported smoking status and smoking intensity. And, “given that our study was observational, we cannot infer causality and we cannot exclude residual confounding,” they wrote. Also, the number of events was modest and CIMT was only measured at the baseline visit.

“In conclusion, in a large prospective cohort of blacks, current cigarette smoking was associated with incident stroke in adjusted models. Furthermore, there was a dose‐dependent increased risk with increased smoking intensity. Overall, there was no significant difference in the risk of incident stroke between past and never smokers, suggesting that smoking cessation may have potential benefits in reducing the incidence of stroke in blacks. Our study builds on previous literature that predominantly investigated these relationships in whites. Blacks are disproportionately affected by cardiovascular disease, including stroke, and have worse outcomes compared with whites. Therefore, our findings have important public health implications,” they wrote.

  1. Be aware than in a large cohort study of blacks followed for more than a decade both current smoking and the number of cigarettes smoked daily were independently association with a greater than 2 times increased relative risk of stroke.

  2. Note that, in the Jackson Heart Study, current smoking and smoking history were associated with accelerative atherosclerosis as measured by carotid intima-media thickness.

Peggy Peck, Editor-in-Chief, BreakingMED™

The JHS (Jackson Heart Study) is supported and conducted in collaboration with Jackson State University the Mississippi State Department of Health, and the University of Mississippi Medical Center, and contracts from the National Heart, Lung, and Blood Institute and the National Institute for Minority Health and Health Disparities.

Oshunbade had no disclosures.

Cat ID: 8

Topic ID: 74,8,730,8,38,143,192,489,925