Heavy smokers who quit remain at significantly increased CVD risk for up to 10 years or more, according to new research. Results suggest that current risk estimators may need revision.
The study appears in the Aug 20 issue of the Journal of the American Medical Association.
Former vs never smokers. CVD risk among former smokers – a group expanding with decline in US smoking rates – may be underestimated. The Atherosclerotic CVD (ASCVD) Risk Estimator Plus does identify former smokers but considers risk identical to that of never smokers after 5 years.
Framingham Heart Study smokers. Retrospective analysis of prospective data to determine association between # yrs since quitting & incident CVD among former smokers vs persistent and never smokers. Outcome measures: Incident CVD (MI, stroke, HF, CVD death) Primary analyses included both cohorts (pooled); restricted to heavy ever smokers (≥20 pack-years).
FHS pooled cohort characteristics. Baseline self-reported smoking habits categorized current, former, never smokers; also used to calculate years since quitting (former smokers), pack-years smoking for ever smokers. Selected a priori and to max comparability with prior research: Established FHS CVD risk factors: age, sex, SBP, HTN Rx use, diabetes mellitus, total cholesterol, plus BMI, EtOH, education level (may confound smoking/CVD risk association).
Top-line results based on 4115 current smokers. 38.6% quit, never relapsed. 51.4% continued to smoke until CVD/censored. Most (84.7%) baseline former smokers stayed abstinent during follow-up. Among baseline ever smokers, 591 relapsed (ie, began again after reporting abstinence during at least 1 clinic visit). Abstinence periods, range: 0 to 68 yrs (median, 3 yrs; interquartile range, 0-15 yrs).
First CVD events (median follow-up 26.4 yrs) in pooled FHS cohort-2435. Approximately twice as many among original cohort (1612) vs offspring (823). Vs current smoking: quitting within 5 yrs was associated with significantly lower risk/rates of incident CVD. Vs never smoking: former heavy smoking was associated with greater CVD risk until 10-15 yrs after cessation.
Former heaving smoking vs never smoking. It took 10-15 years (pooled cohort) (5 to 10 years in the original cohort and ≥25 years in the offspring cohort) following cessation for former heavy smoking (vs never smoking) to cease being significantly associated with elevated CVD risk.
Nurses' Health Study for comparison. The current study's upper estimate of time course is 10 yrs longer than in Nurses' Health Study results for CHD, CVD death and >20 yrs longer than in prior reports for CHD, stroke.
5 years and all clear message challenged. The current data do not support the assertion that 5 years after smoking cessation CVD risk is similar for past smokers vs never smokers. Authors suggest improving CVD risk estimates among former smokers with frequent long-term smoking exposure assessment (status, intensity, abstinence periods, and relapse); objective & time-updated assessment of other CVD risk factors; continuous CVD incidence surveillance.
Compared with never smokers, heavy smokers remain at increased CVD risk for up to a decade or more, according to a new study. We offer a top-line look at the retrospective analysis of Framingham Heart Study participants in the slides below, followed by the authors' recommendations for improving CVD risk surveillance among past tobacco users.
