Cardiovascular risk may take decades to erase after quitting for heavy smokers
Key takeaways:
- Light ex-smokers had a similar cardiovascular risk to never-smokers after 10 years of cessation.
- Heavy ex-smokers needed over 25 years of cessation to match the cardiovascular risk in never-smokers.
Ex-smokers with a light lifetime smoking burden had a CVD risk shortly after quitting similar to those who have never smoked, results from a cohort analysis showed.
However, findings from the retrospective study suggest that ex-smokers who smoked heavily may need to restrain from smoking for more than 25 years to have a cardiovascular risk similar to those who have never smoked.
The time passed after quitting smoking and the subsequent changes in (CVD) risk “are not properly reflected in guidelines and contemporary clinical practice,” according to Jun Hwan Cho, MD, from the Chung-Ang University Gwangmyeong Hospital in the Republic of Korea, and colleagues.
“For instance, the latest clinical CVD risk stratification tool does not properly estimate the potential CVD risk of ex-smokers,” they wrote in JAMA Network Open. “Indeed, the time elapsed after smoking cessation and lifetime smoking burden may affect CVD risk for a certain period.”
The researchers examined the risk for CVD among ex-smokers after cessation, as well as CVD risk based on the lifetime smoking burden of ex-smokers. They analyzed information from from the Korean National Health Insurance Service database from 2006 to 2008.
The study included 5,391,231 participants, with a mean follow-up of 4.2 years. Of the sample, 15.8%, 1.9% and 82.2% were current, former and never-smokers, respectively.
Cho and colleagues found a dose-dependent relationship between incident CVD and smoking regardless of continued smoking.
They also reported higher incidences of CVD among both former and current smokers than among never smokers, with the adjusted HRs for CVD of 1.13 (95% CI, 1.1-1.15) for former smokers and 1.22 (95% CI, 1.02-1.24) for current smokers, both compared with never smokers.
Overall, ex-smokers had a significantly lower risk for CVD within 5 years of quitting smoking (HR = 0.96; 95% CI, 0.92-0.99) and 5 to 10 years of quitting (HR = 0.91; 95% CI, 0.87-0.95). However, ex-smokers had a significantly greater risk for CVD vs. never-smokers that persisted up to 20 years of quitting.
The researchers noted that ex-smokers with a lifetime smoking burden of less than 8 pack-years — considered light ex-smokers — had a significant decrease in cardiovasdcular disease risk within 10 years of cessation, with the risk similar to those of never-smokers.
In comparison, ex-smokers with a lifetime smoking burden of at least eight pack-years showed a significantly greater risk for CVD vs. never-smokers after beginning cessation, with the risk similar to those of current smokers until 20 years.
Ultimately, these heavy ex-smokers required over 25 years of cessation for the residual CVD risk to disappear.
Cho and colleagues highlighted several clinical implications that arise from the findings. For example, they noted that the dose-dependent association “[emphasizes] the importance of preventing smoking initiation altogether.”
For people who start smoking but do not reach the “point of no return” — in this case, 8 pack-years — “they may quit smoking with marked clinical improvements expected soon after quitting,” they wrote.
Regarding heavy ex-smokers, “[they] should be considered to have a CVD risk equivalent to that of patients who continue to smoke, and management should be planned accordingly,” the researchers concluded.