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.