Introduction

Smoking remains a strong risk factor for premature death. This study examines the associations of nondaily smoking, daily smoking, and smoking cessation with the risks of mortality from all causes, cardiovascular disease, and cancer.

Methods

This study used data from the National Health and Nutrition Examination Survey, a population-based, cross-sectional study. Data analysis was conducted in the U.S. from January to October 2020. Cox proportional hazard regression models were used to obtain adjusted hazard ratios.

Results

During 255,100 person-years of follow-up, 2,008 participants died (347 from cardiovascular diseases and 501 from cancer). A significant increase in the risk of all-cause mortality was observed for nondaily smokers (hazard ratio=1.50, 95% CI=1.08, 2.08) compared with that for those who had never smoked. For daily smokers, the adjusted hazard ratios for all-cause mortality were 1.54 (95% CI=1.24, 1.90) for those smoking <20 cigarettes per day, 2.09 (95% CI=1.65, 2.63) for those smoking 20–40 cigarettes per day, and 2.78 (95% CI=1.75, 4.43) for those smoking ≥40 cigarettes per day. An increased risk of cardiovascular disease and cancer mortality was also observed for daily smokers. Former smokers with ≥5 years since cessation had a lower risk of all-cause mortality than current smokers.

Conclusions

This study suggests that nondaily smokers have a higher risk of all-cause mortality. The association of daily smoking with the risk of mortality increased as the number of cigarettes smoked per day increased. Among former smokers, the risk decreased with longer cessation. Tobacco control efforts should be targeted not only toward daily smokers but also toward nondaily smokers to reduce the risk of premature death owing to smoking.