An analysis of data from nearly two dozen long-term studies finds that even light smokers have a significantly higher risk of heart disease and death than never-smokers, even years after quitting. Michael Blaha of the Ciccarone Johns Hopkins Center for Cardiovascular Disease Prevention, USA, and colleagues report these findings on November 18u in the open access journal PLoS Medicine.
Previous research has shown that cigarette smoking increases the risk of heart disease, but the exact relationship between how much a person smokes and their risk is still unclear, especially for light smokers. Today, more people are smoking fewer cigarettes, but it’s still important to understand the cardiovascular risks and long-term benefits of quitting, even for people who don’t smoke a pack a day.
Blaha’s team analyzed data from more than 300,000 adults enrolled in 22 longitudinal studies – which include the following groups of people over time – for up to 19.9 years. In that time, they recorded more than 125,000 deaths and 54,000 cardiovascular events, including heart attacks, strokes and heart failure. The analysis showed that even very light smoking, defined as two to five cigarettes a day, was associated with a 50% higher risk of heart failure and a 60% higher risk of death from any cause, compared to never smoking. A person’s risk of cardiovascular events decreased significantly in the first decade after quitting smoking and continued to decrease over time. However, even up to three decades later, ex-smokers may still be at higher risk compared to never-smokers.
Considering that even occasional or very light smoking significantly increases a person’s risk of cardiovascular disease and death, researchers conclude that stopping smoking at younger ages is the best way to reduce risk, rather than reducing the number of cigarettes smoked each day. These findings reinforce established public health guidelines—that smokers should quit smoking as early as possible rather than simply cut down—and emphasize the importance of smoking prevention programs.
The authors add, “This is one of the largest studies of cigarette smoking to date, using the highest quality data in the cardiovascular epidemiology literature. It is remarkable how harmful smoking is – even low doses of smoking carry major cardiovascular risks. In terms of behavior change, it is imperative to stop smoking as early in life as possible, as the time elapsed since complete cessation is more important the prolonged exposure to a smaller amount of cigarettes each day.”
