Two-year effects of a school-based prevention programme on adolescent cigarette smoking in Guangzhou, China: A cluster randomized trial

Background: The prevalence of adolescent smoking has been increasing rapidly in China. Theory-based smoking prevention programmes in schools may be an effective approach in preventing smoking among Chinese adolescents. Methods: A school-level cluster randomized controlled trial was conducted among 7th and 8th grade students (N = 2343) in four junior high schools in southern China during 2004-06. The theory-based, multi-level intervention was compared with the standard health curriculum. Outcome measures comprised changes in students' smoking-related knowledge, attitudes and behaviour. Results: The mean knowledge scores from baseline to the 1- and 2-year follow-ups increased more in the intervention group than in the control group, whereas there was little change in attitude scores. At the 1-year follow-up (the total sample), the interventions reduced the probability of baseline experimental smokers' escalating to regular smoker [7.9 vs 18.3%; adjusted odds ratio (OR) 0.34, 95% confidence interval (CI) 0.12-0.97, P = 0.043], but did not reduce the probability of baseline non-smokers' initiating smoking (7.9 vs 10.6% adjusted OR 0.86, 95% CI 0.54-1.38, P = 0.538). At the 2-year follow-up (only 7th grade students), similar proportions of baseline non-smokers initiated smoking in the intervention group and the control group (13.5 vs 13.1%), while a possibly lower proportion of baseline experimental smokers escalated to regular smoking in the intervention group than the control group (22.6 vs 40.0% adjusted OR 0.43, 95% CI 0.12-1.57, P = 0.199). Conclusions: This multi-level intervention programme had a moderate effect on inhibiting the escalation from experimental to regular smoking among Chinese adolescents, but had little effect on the initiation of smoking. The programme improved adolescents' smoking-related knowledge, but did not change their attitudes towards smoking.