Effect of self-reported home smoking restriction on smoking initiation among adolescents in Taiwan: a prospective cohort study

OBJECTIVE The aims of this study were to investigate the influence of home smoking restriction (HSR) and the modified effect of parental smoking on smoking initiation among adolescents. DESIGN Prospective Cohort Study. SETTING Junior high school in Keelung City, Taiwan. PARTICIPANTS This study collected and evaluated primary data from the Adolescent Smoking and Other Health-Related Behaviour Survey conducted in Keelung City, which aimed to investigate smoking and health-related behaviours in junior high school students (2008-2009). Data on students free of smoking in 2008 and following them until 2009 (n=901) to ascertain whether they had started smoking were analysed with logistic regression mode to examine the proposed postulates. MAIN OUTCOME MEASURE The outcome variable was smoking initiation, which was defined as smoking status (yes/no) in the 2009 follow-up questionnaire. The main independent variable was HSR obtained from an adolescent self-reported questionnaire. Information on parental smoking was measured by adolescents self-reporting the smoking behaviour of their father and mother. RESULTS The rate of HSR was 29.79% among 7th grade adolescents. The effect of HSR on smoking initiation in adolescents was statistically significantly modified by paternal smoking (p=0.04) but not by maternal smoking (p=0.54). The effect of HSR on smoking initiation was small for fathers with the habit of smoking (OR=0.89, 95% CI (0.42 to 1.88)), but the corresponding effect size was 3.2-fold (OR=2.84, 95% CI 1.19 to 6.81) for fathers without the habit of smoking. CONCLUSIONS Paternal smoking behaviour may play an interactive role with HSR in preventing smoking initiation among Taiwanese adolescents.