Impact of weight change after quitting cigarettes on all-cause and cause-specific mortality in middle-aged male smokers: national health screening cohort study

Background: We aimed to investigate the association between weight change after smoking cessation and the risk of all-cause and cause-specific mortality among middle-aged male smokers. Methods: We conducted a prospective cohort study using the National Health Insurance Service National Health Screening Cohort (NHIS-HealS) database. Male Participants (n=102,403) without critical conditions aged between 40 and 79 at baseline who underwent biennial health examination were included in this study. Participants were categorized into continued smokers, recent quitters (within 4 years), long-term quitters (more than 4 years), and never-smokers based on the self-reported smoking status. Weight change was determined by the change of Body Mass Index (BMI) between the first (2002-2003) and second (2004-2005) health examination records. We followed patients from January 1, 2006 to December, 31, 2013. To assess the risk of all-cause, cancer, cardiovascular disease (CVD) mortality, and non-cancer, non-CVD mortality according to smoking cessation and weight change, we computed Hazard Ratio (HR) and 95% Confidence Interval (95% CI) using Cox proportional hazard models. Results: Severity of weight gain was more prevalent among recent quitters compared to long-term quitters. After adjusting for covariates and weight change, both recent quitters (HR:0.74; 95% CI: 0.63-0.87) and long-term quitters (HR:0.53; 95% CI:0.45-0.61) had decreased risk of all-cause mortality compared to continued smokers. Similarly, both recent and long-term quitters had decreased risk of cancer, CVD, non-cancer, and non-CVD death regardless of weight change following smoking cessation. Compared to continued smokers, non-smokers also had a lower risk of overall and cause-specific death. Conclusions: Post-cessation weight change did not modify the protective association of smoking cessation with reduced risk of all-cause and cause-specific death. From a public health perspective, smoking cessation program may contribute to reducing risk of death in middle-aged male smokers despite the concern on weight change after quitting smoking.