New Delhi, Nov 3 (IANS): Smoking and cardiovascular disease (CVD) risk have a dose-dependent association, with light ex-smokers having a CVD risk similar to that of never-smokers relatively soon after smoking cessation, a new study has revealed.

For heavy ex-smokers, greater than 25 years might be required for the residual CVD risk to align with that of never-smokers, said the study published in the journal JAMA Network Open.

The study sought to find an answer to the question: How long does a person need to quit smoking to lower cardiovascular disease (CVD) risk?

In the cohort study of extracted data from the Korean National Health Insurance Service database with more than 53 lakh participants, ex-smokers who had accumulated less than 8 pack-years (PY) did not exhibit a significantly increased risk of CVD compared with never-smokers.

However, for ex-smokers who had accrued at least 8 PY, more than 25 years were needed for the residual CVD risk of smoking to disappear, the findings showed.

The results suggest that ex-smokers with at least 8 PY should be considered at equivalent risk of CVD as current smokers, and management should be planned accordingly, the authors said.

The study evaluated the associations among smoking cessation, lifetime smoking burden and CVD risk according to the number of years elapsed after smoking cessation.

“These results have important implications for clinical practice and public health. Regardless of smoking cessation status, smoking and CVD risk exhibit a clear dose-response association, emphasizing the importance of preventing smoking initiation altogether,” said authors.

For people who start smoking, if their cumulative smoking amount does not exceed a certain threshold or the so-called point of no return -- 8 PY in this study -- they may quit smoking with marked clinical improvements expected soon after quitting.

Hence, the results suggest that successful smoking cessation before reaching 8 PY promises considerable public health benefits.