Does birthplace affect age of smoking onset among Chinese youth in Hong Kong? : A proportional hazards model analysis

Data are needed regarding age pattern and influential factors of early smoking onset among adolescents in Hong Kong for more effective smoking prevention. A random sample of 6,486 youth in grades 7, 8 and 9 were derived from the project Chinese Student Health Survey. Hazards of smoking onset were estimated using survival analysis method. Mediation effect was assessed using logistic regression and proportional hazards regression models. The hazard level of smoking initiation increased with age, it was rather low (<1.5%) prior to 10 years of age, peaked at age 12 (approximately 3%) before it declined. Boys were slightly more likely than girls to initiate smoking at age 10 or younger and after age 12 and older. Students who were not born in Hong Kong were more likely to start smoking across ages 5 through 14. The migration-related increases in the hazards of smoking onset were mediated primarily by parental smoking and parental monitoring. The likelihood of smoking onset peaked at 12 years of age among Hong Kong youth, suggesting that effective adolescent smoking prevention in Hong Kong should not be later than 12 years of age. Given the growing number of immigrants in Hong Kong, immigrant children and their parents should be the priority population for smoking prevention. The relatively greater hazards of smoking onset among Chinese girls in Hong Kong indicate that more attention be paid to the reduced gender differences in future tobacco research and prevention.