Patterns of Long-term Cigarette Smoking Behavior on CVD Risk: Implications for Clinical Practice and Public Health

Project Summary: The goal of the current study is to quantify cardiovascular disease (CVD) risk associated with smoking cessation and changes in smoking patterns among a diverse cohort of US adults. Individuals who currently smoke, particularly those who smoke heavily or have smoked for a number of years, may feel that cessation is unattainable. For those who struggle to quit smoking, substantial reduction in cigarettes per day (CPD) as a step toward smoking cessation may be a more achievable goal. However, CPD reduction is not commonly advocated in public health messaging, and whether risk benefit is realized upon CPD reduction without cessation, is debated. For smokers who do quit, their CVD risk attributable to smoking takes at least 5 years and potentially 10 to 15 years, to attenuate to that of a never smoker. Whether the time-course of risk reduction differs by pack-years smoked remains unknown. Finally, it is imperative that our risk assessment tools accurately capture the impact of long-term smoking behaviors on CVD risk. However, the American Heart Association’s newly released Predicting Risk of Cardiovascular Disease EVENTS (PREVENT) equations distinguish only between current and non-current smokers when estimating 10- and 30-year CVD risk (i.e., former and never smokers are combined into a single group) and neither years since quitting nor pack-years smoked are included. To this end, we will incorporate data from six existing cohort studies to address these knowledge gaps in a racially, ethnically, and socioeconomically diverse sample. First, we will incorporate repeated measures of smoking status and intensity to ascertain whether reduction in CPD results in decreased CVD risk (Aim 1). Then, we will estimate the number of years of cessation that are required for former smokers’ risk to approximate that of a never smoker. We will also determine whether this time-course differs by pack-year smoked (Aim 2). Lastly, we will determine whether adding an indicator of former smoking status, pack-years smoked, and years since quitting to the PREVENT equations improves CVD risk prediction. Successful completion of the proposed research has implications for how physicians treat their currently and formerly smoking patients regarding CVD risk reduction, which could decrease years of life lost due to cigarette smoking. Findings may also impact public health messaging which could include information on lowering CVD risk via smoking reduction on the path to full cessation.