Knowledge and Concerns About Smoking-Related Health Risks: A Cross-Sectional Analysis of the 2021 International Tobacco Control Japan and Korea Surveys.

INTRODUCTION: This cross-sectional study examined: (i) knowledge of smoking-related health risks among adults who currently and formerly smoke; (ii) concerns about personal health damage from smoking among adults who currently smoke; (iii) sociodemographic predictors of knowledge; and (iv) associations between knowledge and concerns in Japan and the Republic of Korea. METHODS: Data from the 2021 International Tobacco Control Surveys included adults (aged ≥ 20, ≥ 19 respectively) in Japan (n = 2956 currently smoke, n = 852 formerly smoke) and Korea (n = 3776 currently smoke, n = 194 formerly smoke). Primary outcomes included knowledge of smoking-related health risks (six consistently measured: stroke, heart disease, lung cancer, emphysema, impotence, early death), categorised as correct or incorrect, summed into a knowledge index score and concerns about smoking damaging their own health. Survey-weighted analyses examined country and smoking status differences and associations between knowledge, concerns and sociodemographic characteristics. RESULTS: Among adults who currently smoke, knowledge of lung cancer was highest (Japan: 82.8%, Korea: 92.2%); lowest were impotence in Japan (35.7%) and heart disease in Korea (69.6%). Adults who formerly smoked had higher knowledge than those who currently smoke in Japan (4.74 [4.50-4.97] vs. 4.00 [3.82-4.18]) but not in Korea (5.05 [4.39-5.72] vs. 4.69 [4.47-4.90]). Japanese adults who currently smoke had lower knowledge and fewer concerns than their Korean counterparts (p < 0.05). Greater knowledge predicted increased concerns in both countries (OR = 1.27 [1.20, 1.35]). Only in Japan were younger age (B = 0.59 [0.06, 1.13]) and moderate income (B = 0.41 [0.16, 0.66]) associated with greater knowledge. DISCUSSION AND CONCLUSIONS: The observed differences in knowledge and concerns about smoking-related health risks between Japan and Korea may reflect their contrasting tobacco control policies.