Smoking Cessation Found to Lower Risk of Cardiovascular Disease

Smoking cessation in heavy cigarette smokers can reduce the risk of cardiovascular disease (CVD) by 39% within 5 years, according to a study published last week in JAMA.

CVD risk in smokers is an unclear issue that prior research has failed to provide an accurate timetable for. Lead study author Meredith Duncan, MA, database administrator at the Vanderbilt University Medical Center, discussed the confusion surrounding smoking cessation and reduced CVD risk as current standards use potentially misleading data in a statement. “Previous studies have shown the association between quitting and reduced CVD risk, but the current Atherosclerotic CVD Risk Calculator, which is routinely used in clinical practice, considers former smokers’ risk to be similar to that of never smokers after 5 years of cessation,” said Duncan.

Researchers used data from a longitudinal study of men and women from Framington, Massachusetts, deemed the Framingham Heart Study (FHS), which includes original cohorts dating back to 1948, as well as their children and grandchildren. Prospective data from 1954 to 2014 determined the effect of lifetime smoking and smoking cessation on the risk found in CVD subtypes myocardial infarction, stroke, CVD death, and heart failure.

A total of 8770 subjects, of which 3805 represented the original cohort and 4965 represented the offspring cohort, were examined by researchers:

• The mean age of subjects in the pooled cohort was 42.2 years; 56% were female
• Exposure was determined by time-updated self-reported smoking status, years since quitting, and cumulative pack-years
• Heavy cigarette smokers were distinguished as having a 20 pack-year history

Following 26.4 median follow-up years, first instances of CVD were found in 2435 subjects. A total of 1612 instances occurred in the original cohort, 665 of which were among heavy smokers, and 823 occurred in the offspring cohort, 430 of which were among heavy smokers. The pooled cohort demonstrated a significant difference in incidence rate (IR) of CVD per 1000 person-years (IR=-4.51; 95% CI, -5.90 to -2.77) between current smokers (IR=11.56; 95% CI, 10.30-12.98) and former smokers who quit within 5 years (IR=6.94; 95% CI, 5.61-8.59) with an additional lower risk of incident CVD (hazard ratio (HR)=0.61; 95% CI, 0.49-0.76).

While former smokers exhibited a significant decrease in CVD risk after 5 years when compared with current smokers, the study suggests that 10-15 years of quitting smoking is needed for greater CVD risk found in smokers to subside when compared with non-smokers.

• IR for non-smokers (5.09; 95% CI, 4.52-5.74)
• IR for subjects quitting within 10 to <15 years (6.31; 95% CI, 4.93-8.09)
• IR difference (1.27; 95% CI, -0.10 to 3.05); HR (1.25; 95% CI, 0.98-1.60)

Senior study author Hilary Tindle, MD, MPH, medical director of the VUMC Tobacco Treatment Service and founding director of the Vanderbilt Center for Tobacco Addiction and Lifestyle, stressed the importance for smokers to quit through the study’s correlating CVD risk. “The cardiovascular system begins to heal relatively quickly after quitting smoking, even for people who have smoked heavily over decades,” said Tindle.

The study’s findings represent a contradiction to information being given to former smokers in clinical practices. A limitation found in the study, however, is its use of predominantly white individuals of European ancestry as it may hint to differentiating CVD risk for smokers of other races. As cigarette smoking is responsible for 20% of CVD deaths in the U.S., it is vital for patients and physicians to fully comprehend the risk associated with each patient’s smoking history.

“Full recovery could take years, so now is a great time to quit smoking and take other steps toward heart health,” said Tindle.

Reference

Duncan MS, Freiburg MS, Greevy RA Jr, et al. Association of Smoking Cessation With Subsequent Risk of Cardiovascular Disease. [published online August 20, 2019]. JAMA. doi: 10.1001/jama.2019.10298