A new study led by researchers at Johns Hopkins Medicine and funded by the National Heart, Lung, and Blood Institute has found that reducing the number of cigarettes smoked does not remove the risk of cardiovascular disease. The research highlights that quitting smoking altogether is the most effective way to improve heart health.
Cigarette smoking remains a leading cause of preventable illness and death in the United States. Data from the Centers for Disease Control and Prevention show that more than 16 million Americans are living with diseases caused by smoking.
The study aimed to clarify how different patterns of smoking—such as duration, intensity, and time since quitting—affect risks related to heart and vascular health. Results were published on November 18 in PLOS Medicine. The research involved analysis of data from 22 cohort studies, combining information on over 323,000 adults who were followed for nearly 20 years. During this period, there were more than 125,000 deaths and over 54,000 cardiovascular events recorded among participants.
Participants had an average age of about 60 years; women made up 76% of the group. Fourteen percent were current smokers, while about half had previously smoked conventional cigarettes.
Researchers used statistical models to adjust for factors such as age, sex, race, ethnicity, education level, body mass index, diabetes status, history of coronary heart disease at baseline, and alcohol use.
"This study shows that even low levels of smoking - for example, only a few cigarettes a day - carry substantial cardiovascular risks," says Blaha. Quitting completely - not just cutting back - provides the greatest health benefit."
The findings also provide estimates showing how much risk current and former smokers face based on how long they have smoked, how many cigarettes they smoke daily, and how long it has been since they quit.
"Our findings illustrate the complex relationship between how much someone has smoked over time and how long it has been since they quit," says Blaha. "These results, which highlight the strong predictive value of longer time since quitting, reinforce the critical need to educate the public and promote early smoking cessation as one of the most effective strategies to reduce the risk of this deadly disease."
Erfan Tasdighi led the study during his time at Johns Hopkins Medicine; he is now at Rutgers New Jersey Medical School. Funding came from both the U.S. Food and Drug Administration and the National Heart, Lung, and Blood Institute.
