Smoking cessation cut CVD risk faster than previous estimates

DALLAS — New study results indicate that older adults who smoked fewer than three packs of cigarette per day for up to 10 years or fewer than one pack per day for 30 years lowered their risks for HF or death related to HF, MI and stroke to the same level as never-smokers within 15 years after quitting.

Previous research indicated that the CV risks for former smokers who smoked less than 32 pack-years were similar to risks for never-smokers 15 years after quitting, researcher Ali Ahmed, MD, MPH, of the University of Alabama at Birmingham, told Cardiology Today. Pack-years are calculated by multiplying the number of years a person smoked by the number of packs per day that he or she smoked.

Ahmed and colleagues analyzed 3,410 participants from the Cardiovascular Health Study who were free of HF at baseline. The study population included 2,557 never-smokers and 853 former smokers who quit within the past 15 years (median, 8 years). Former smokers were stratified by smoking intensity, with heavy smoking defined as at least 32 pack-years. The follow-up period was 13 years.

Risk for HF

Unadjusted rates of incident HF were 20% for never-smokers, 18% for former light smokers and 21% for former heavy smokers. After adjustment for age, sex and race, the risk for incident HF for former light smokers was similar to never-smokers (HR=1.04; 95% CI, 0.79-1.37), but former heavy smokers had a higher risk compared with never-smokers (HR=1.29; 95% CI, 1.04-1.6).

The researchers observed a similar effect for CV mortality, which occurred in 17% of never-smokers, 14% of former light smokers and 22% of former heavy smokers. After adjustment for age, sex and race, rates of CV mortality were similar between former light smokers and never-smokers (HR=1.07; 95% CI, 0.78-1.45), but former heavy smokers had a higher risk compared with never-smokers (HR=1.81; 95% CI, 1.45-2.24).

Risk for death

Former light and heavy smokers were at greater risk for all-cause mortality and non-CV mortality compared with never smokers, the researchers found. After the adjustment for age, sex and race, the HRs were:

All-cause mortality for former light smokers compared with never-smokers: HR=1.38; 95% CI, 1.15-1.65.
All-cause mortality for former heavy smokers compared with never-smokers: HR=1.95; 95% CI, 1.7-2.24.
Non-CV mortality for former light smokers compared with never-smokers: HR=1.62; 95% CI, 1.29-2.02.
Non-CV mortality for former heavy smokers compared with never-smokers: HR=2.07; 95% CI, 1.73-2.47.

“This is likely because of higher risk for death due to non-CV causes such as lung cancer, [chronic obstructive pulmonary disease] and emphysema among smokers,” Ahmed said in an interview. “Smoking is the single biggest preventable cause of cancer and is responsible for many cancers other than lung cancer.”

The researchers previously reported in 2010 and 2011 that former heavy smokers remained at increased risk for incident HF and death compared with never-smokers despite over 15 years of cessation, but they too had significantly lower risk for all-cause mortality after more than 15 years of abstinence, compared with current smokers, Ahmed told Cardiology Today.

The mechanism linking smoking to increased risk for CV events is “mostly inflammation and atherosclerosis,” Ahmed said. “That is why this is a reversible process, unless it reaches a threshold of no return. The non-cardiovascular effects are more difficult to reverse. The bottom line is data based on older adults send an important message to the younger generation: If you are a non-smoker, do not start, but if you are a smoker, quit and quit early.” – by Erik Swain

For more information:

Ahmed AA. Abstract #18709. Presented at: the American Heart Association Scientific Sessions; Nov. 16-20, 2013; Dallas.

Disclosure: Ahmed reports no relevant financial disclosures.