Continued smoking from younger age may confer higher risk for CV mortality
Compared with never smokers, current smokers had elevated risk for CV mortality, which was higher the earlier a person began smoking, researchers reported.
People who quit smoking had elevated risk for CV mortality compared with never smokers but less risk compared with current smokers, with the risk lower for those who quit at a younger age, according to the researchers.
“The findings from this study are an urgent reminder that smoking remains one of the biggest threats to CV health in the United States, in addition to many other countries around the world,” Blake Thomson, MPhil, DPhil, epidemiologist at the University of Oxford, England, told Healio. “Although smoking substantially increases the risk of premature death from heart disease or stroke, especially for those who began at an early age, quitting reverses that risk. Clinicians should drive home the point that quitting can avoid much, even most, of the risk associated with continued smoking.”
For this study, published in the Journal of the American Heart Association, researchers used the annual U.S. National Health Interview Surveys from 1997 to 2014, to assess the medical history, demographic details and habits, including smoking, drinking and physical activity, among U.S. adults. Participants were followed for mortality through 2015.
Current smokers were categorized by the age they began smoking regularly (younger than 10 years, 10 to 14 years, 15 to 17 years, 18 to 20 years or older than 20 years).
Ex-smokers were categorized by the age they last smoked regularly (aged 15 to 34 years, 35 to 44 years, 45 to 54 years or 55 to 64 years).
Occasional smokers and smokers who quit within 5 years of death were excluded.
Overall, 390,929 participants were included in this analysis (mean age, 47 years; 56% women).
Smoking from a young age
Among current smokers, 2% began smoking before age 10 years and 19% from age 10 to 14 years.
Investigators observed that the rate of CV mortality increased among current smokers who began smoking at younger ages compared with never smokers:
- Younger than 10 years (RR = 4.89; 95% CI, 3.9-6.12);
- at 10 to 14 years (RR = 2.98; 2.68-3.31);
- at 15 to 17 years (RR = 2.87; 2.64-3.13);
- at 18 to 20 years (RR = 2.66; 2.41-2.94); and
- at older than 20 years (RR = 2.45; 2.18-2.75).
Cessation at any age
“It doesn't matter if you've smoked for a few months or for several decades, quitting smoking has tremendous health benefits and it is never too late to quit, but the sooner the better,” Thomson said in an interview. “Quitting smoking is one of the best investments you can make when it comes to your health, and the health benefits only grow with time. The sooner you quit, the greater the health gains. Today is the day to stop smoking.”
The rate of CV mortality decreased among ex-smokers who quit at younger ages compared with current smokers (RR = 2.8; 2.66-2.95):
- at 15 to 34 years (RR = 0.91; 95% CI, 0.81-1.02);
- at 35 to 44 years (RR = 1.19; 95% CI, 1.06-1.33);
- at 45 to 54 years (RR = 1.58; 95% CI, 1.42-1.76); or
- at 55 to 64 years (RR = 1.69; 95% CI, 1.47-1.93).
“Previous research in the U.S. and elsewhere has shown that smokers lose an average of 10 years of life expectancy compared to nonsmokers, but those who quit by around age 40 can regain 9 or even all 10 of those years,” Thomson told Healio. “Even at older ages, quitting smoking saves lives, and is an urgent public health priority.
“We hope to further examine the hazards of childhood smoking in other populations globally, and also to examine the relationship between childhood smoking and other health outcomes, such as respiratory disease and cancer,” Thomson said in an interview. “We also intend to further examine the benefits of quitting smoking in the U.S. and other populations, for CVD and for a number of other health outcomes.