This did not change the effect (OR = 0.67, 95% confidence interval (95% CI) = 0.47–0.97). Stratified analyses showed that the effects on intention and smoking behavior were only significant in girls. The intervention girls were significantly less inclined to start smoking (B = 0.21, 95% CI = 0.04–0.37) and to smoke (OR = 0.44, 95% CI = 0.24–0.81) than the

DAPT control girls in secondary school. There were no differences for parental socio-economic status or educational level of the student. To assess mediating effects, we also analyzed the relationship between the change in the behavioral determinants, in intention not to smoke, and in smoking behavior. An increased self-efficacy in refraining from smoking (B = 0.17, Regorafenib cell line 95% CI = 0.12–0.21), an increased awareness of both disadvantages (0.50, 95% CI = 0.37–0.63) as advantages of smoking (0.19, 95% CI = 0.08–0.29), a decrease in the social pressure to smoke (0.12, 95% CI = 0.06–0.18), and in the perception of smoking behavior in diffuse (0.25, 95% CI = 0.13–0.37) and nuclear network (0.35, 95% CI = 0.05–0.65) were associated with an increased intention to refrain from smoking. Smoking in secondary school was related to a decrease in the intention to refrain from smoking (OR = 0.59, 95% CI = 0.49–0.71) and in the perceived disadvantages of smoking (OR = 0.28, 95% CI = 0.16–0.49) and

to an increase in perceived smoking in the diffuse network (OR = 0.45, 95% CI = 0.30–0.67). The objective of this study was to assess the immediate and longer term effects of an education program to prevent the onset of smoking in the transition phase between elementary and secondary school. The education program seemed to have limited effect during elementary school. Midway the first class of secondary school, the children in the intervention group, however, indicated that

Tryptophan synthase they experienced less social pressure and had more positive attitudes towards non-smoking than the students in the control group. But above all they had a higher intention not to smoke and they less often smoked than the students in the control group, particularly the girls. A possible explanation for this seemingly delayed effect is that, in elementary school, students both in the intervention and in the control group were still against smoking. Just a few children smoked or experimented with smoking; both groups scored high on the determinants towards non-smoking, causing only limited changes in these determinants. These results also partly confirm the results of Côté et al. (2006), who found no effect on smoking behavior 2 and 8 months after an intervention in elementary school. In their study, however, shortly after the intervention, more behavioral determinants changed than in our study. We observed a change in behavioral determinants and in behavior only in secondary school.