Alcohol dependence trajectories and smoking cessation among Korean men who smoke: A secondary data analysis from the Korean longitudinal study of aging dataset

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INTRODUCTION: Alcohol dependence may hinder smoking cessation, yet few studies have examined how long-term patterns of alcohol use influence quit outcomes. This study assessed how alcohol dependence trajectories affect smoking cessation among Korean men who smoke. METHODS: We performed a secondary analysis using waves 1-7 (2006-2018) of the Korean Longitudinal Study of Aging (KLoSA). Latent class growth analysis (LCGA) identified alcohol dependence trajectories among 2356 men aged ≥45 years who participated in at least three consecutive waves. Multinomial logistic regression (n=1959) was used to assess predictors of trajectory class membership, and Cox proportional hazards models (n=1122) were used to evaluate the association between class membership and smoking cessation. Statistical significance was set at a two-sided p<0.05. RESULTS: Three alcohol dependence trajectories were identified: stable low (80.7%), decreasing (14.3%), and increasing (5.0%). Participants in the decreasing (adjusted hazard ratio, AHR=0.77; 95% CI: 0.63-0.95) and increasing (AHR=0.60; 95% CI: 0.42-0.86) groups were less likely to quit smoking than the stable low group. Multinomial regression showed that, compared to non-smokers, both former smokers (AOR=1.83; 95% CI: 1.24-2.70) and current smokers (AOR=2.23; 95% CI: 1.60-3.09) were associated with higher odds of belonging to the decreasing trajectory. Only current smoking was significantly associated with the increasing trajectory (AOR=2.28; 95% CI: 1.36-3.84). In stratified analyses, the inverse association between increasing trajectory and quitting was significant only in those aged 45-54 years. Sensitivity analyses using weighted and complete-case data confirmed the robustness of the findings. CONCLUSIONS: Alcohol dependence trajectories were significantly associated with smoking cessation outcomes, especially among younger individuals. Smoking status was also a significant predictor of trajectory class membership, with current smokers more likely to belong to the increasing trajectory. Integrated interventions addressing both behaviors may improve cessation outcomes in high-risk groups.