African Americans who smoke appear to have more than twice the risk of developing coronary heart disease compared to those who do not smoke, a new study has found. The findings—the first up-close look at the relationship between smoking and coronary heart disease in this population—also examined the risk for plaque buildup in the arteries of African Americans who smoke. Excessive plaque in the arteries is a known predictor of heart attacks and heart failure.
The study, published today in the Journal of the American Heart Association, draws on data from nearly 4,500 participants in the Jackson Heart Study, the largest cohort study investigating cardiovascular disease exclusively in African Americans. That study, as well as the new research, is supported by the National Heart, Lung, and Blood Institute (NHLBI), and the National Institute of Minority Health and Health Disparities (NIMHD), both part of the National Institutes of Health.
Coronary heart disease, the leading cause of death in the world, is the most common type of heart disease. In the United States, it affects more than 20 million adults and causes one in seven deaths, according to the Centers for Disease Control and Prevention. It can develop when plaques build up in the blood vessels that supply the heart. These clogged, or calcified, arteries can limit or block blood flow and increase the risk for heart attack.
Compared to whites, African Americans are more likely to die from coronary heart disease. Cigarette smoking causes inflammation and atherosclerosis, and coronary heart disease. Despite a marked decline in smoking among African American adults in recent years, almost 15% reported current cigarette smoking in 2019. Yet the link between cigarette smoking and coronary heart disease has been understudied in this population.
African Americans have disproportionally higher rates of hypertension, diabetes, and obesity—known risk factors that partly explain the greater death toll from coronary heart disease in this community, according to the researchers.
“But smoking is also a well-documented risk factor, which, combined with the others, suggest that African Americans smokers represent a particularly vulnerable population for this disease,” said lead study author Adebamike Oshunbade, M.D., M.P.H., a postdoctoral research fellow at the University of Mississippi Medical Center in Jackson. “However, our study is the first to focus on the relationship between cigarette smoking and coronary heart disease exclusively among a large cohort of African Americans.”
Given the scant inclusion of African Americans in prior studies, researchers had limited ability to single out the specific effects of smoking, distinct from other risk factors, in this population. But with the Jackson Heart Study cohort of 5,306 participants, Oshunbade and colleagues were able to assess the relationship between smoking, coronary heart disease, and coronary artery calcification in African American adults.
The investigators used coronary artery calcification (CAC) score measurements to assess the degree of calcified plaque buildup in participants’ coronary arteries. CAC score, which is measured by a CT scan, is a key predictor of an individual’s risk for cardiac events like heart attacks.
For the study, 4,432 participants without a history of coronary heart disease at the time (2000-2004), were classified as current smokers, former smokers, or never smokers. After taking into account other risk factors—including smoking intensity, or the number of cigarettes each consumed daily—researchers followed the participants through 2016, tracking the development of coronary heart disease.
The researchers found that, compared to those who never smoked, those who currently smoked had a more than two-fold higher risk of coronary heart disease. Similarly, those who smoke had an increased likelihood of having a higher CAC score.
“Smoking is a modifiable risk factor for cardiovascular disease and 73% of African American adults who smoke want to quit,” said David Goff, M.D., Ph.D., director of the NHLBI’s Division of Cardiovascular Sciences. “However, compared to whites, African American patients are less likely to receive information about smoking cessation treatments that we know can make a difference. Fully addressing tobacco-related disparities requires addressing conditions where people live, work, and play.”
As the authors noted, the study was observational, and the findings do not establish casual links. Additionally, they should not be generalized to people of other races or regions.
Oshunbade, A. et al. Cigarette Smoking, Incident Coronary Heart Disease and Coronary Artery Calcification in African Americans: The Jackson Heart Study. Journal of the American Heart Association. March 2021. DOI: 10.1161/JAHA.120.017320