Smoking Cessation, Weight Change, and CVD Risk

Cigarette smoking is also a major risk factor for cardiovascular disease (CVD) and the leading cause of preventable death in the United States. The risk of CVD can be greatly reduced by smoking cessation, but cessation is also associated with a few adverse effects, most notably weight gain.

In North America, the mean postcessation weight gain varies between 3 and 6 kg. The weight gain occurs within 6 months of cessation and persists over time. Noting that obesity is also a risk factor for CVD, researchers hypothesized that weight gain following smoking cessation might attenuate the benefits of cessation on CVD outcomes.

To test that hypothesis, the researchers recently conducted a prospective community-based cohort study among adults with and without diabetes. They reported study results in JAMA [2013;309(10):1014-1021].

The researchers utilized data from the Framingham Offspring Study (children and spouses of the original Framingham Heart Study cohort) collected from 1984 through 2011. Participants in the Offspring cohort underwent examinations approximately every 4 to 6 years. The current study sample comprised 3251 adult participants who were free of CVD at the beginning of examination 3.

At each examination, self-reported smoking status was assessed and categorized as smoker, recent quitter (≤4 years), long-term quitter (>4 years), and nonsmoker. The researchers then used polled Cox proportional hazards models to estimate the association between quitting smoking and 6-year CVD events. They also tested whether 4-year change in weight following smoking cessation modified the association between smoking cessation and CVD events.

The primary outcome measure was the incidence over 6 years of total CVD events, defined as coronary heart disease, cerebrovascular events, peripheral artery disease, and congestive heart failure.

Following the third examination, the 3251 participants underwent follow-up over the course of 4 subsequent examinations, contributing to 11,148 person-examinations. Smoking prevalence at the third examination was 31%; it decreased to 13% at the eighth examination.

In participants with and without diabetes, weight gain occurred over 4 years. Among those without diabetes, recent quitters gained significantly more weight than long-term quitters, smokers, and nonsmokers (median, 2.7 kg, 0.9 kg, 0.9 kg, and 1.4 kg, respectively; P<.001 for each pairwise comparison). Among those with diabetes, recent quitters also gained significantly more weight than smokers, long-term quitters, and nonsmokers (3.6 kg, 0.9 kg, 0.0 kg, and 0.5 kg, respectively; P<.001 for each pairwise comparison).

Among the cohort without diabetes, the age- and sex-adjusted rates of CVD events were lower for nonsmokers, recent quitters, and long-term quitters compared with smokers (2.43 per 100 person-examinations, 3.22, 3.06 vs 5.89, respectively). Among those with diabetes, the age- and sex-adjusted rates were lower for nonsmokers, recent quitters, and long-term quitters compared with smokers (4.70 per 100 person-examinations, 6.11, 6.53 vs 7.03, respectively).

In the model adjusted for CVD risk factors, the hazard ratio for nonsmokers without diabetes was 0.41, for recent quitters 0.49, and for long-term quitters 0.53, compared with smokers. Adjusting for CVD risk factors and weight change did not significantly change these estimates. Among participants with diabetes, there were similar point estimates that did not reach statistical significance.

In conclusion, the researchers stated, “In this community-based cohort, smoking cessation was associated with a lower risk of CVD events among participants without diabetes, and weight gain that occurred following smoking cessation did not modify this association. This supports a net cardiovascular benefit of smoking cessation, despite subsequent weight gain.”