Abstract 17919: Cigarette Smoking Explains Excess Deaths Associated with Being Underweight among Middle-Aged Korean Men

Introduction: It is unclear whether smoking affects a relationship between being underweight and the risk of all-cause mortality. Hypothesis: We assessed the hypothesis that smoking causes excess mortality among middle-aged Korean men with low body mass index (BMI). Methods: We analyzed data on the body mass index (BMI), smoking status, and all-cause mortality in a population-based cohort study (108,461 Korean men aged 35-59 years as of 1990 and 1992). To minimize the possibility of reverse causality, we excluded men (1) who had reported to have a disease at baseline, (2) whose information on their smoking status had been missing and (3) who had died in 1993-1995. Finally, 95,019 men were enrolled for analysis. The mean follow-up period was 13.7 years. The BMI was divided into five categories according to WHO criteria for Asians: underweight, 2 ; normal weight, 18.5-22.9 kg/m 2 ; overweight at risk, 23.0-24.9 kg/m 2 ; obese I, 25.0-29.9 kg/m 2 ; obese II, ≥30.0 kg/m 2 . Smoking status was categorized into ‘current smoker’, ‘ex-smoker’ and ‘non-smoker’. We divided all participants into 15 groups based on the BMI and smoking status for analysis. The reference group was non-smokers with normal weight. The main outcome variable was all-cause mortality. Results: The number of total mortality was 6297 (6.63%). Mortality rates were 4.74% (n=957) among non-smokers, 5.47% (n=1081) among ex-smokers, and 7.74% (n=4259) among current smokers. Compared to non-smokers with normal weight, current smokers who were also underweight showed a significantly higher HR (3.55; p Conclusions: Excess mortality associated with being underweight may be caused by current smoking among middle-aged Korean men.