Background: This paper examines the effectiveness of the "Smoke-Free Class Competition" in delaying the onset of smoking in adolescence. Each participating class must decide if they want to be a "smoke-free class" for the 6-month period from fall to spring. Classes monitor their (non-)smoking behavior and report it to the teacher regularly. Classes in which pupils refrain from smoking for this period of time participate in a prize draw, in which they can win a number of attractive prizes.
Methods: To evaluate the effectiveness of the competition, a sample of 131 participating and nonparticipating classes (number of pupils 2,142; mean age 12.9 years, SD = 0.98) was compared with regard to their smoking behavior. Smoking status was determined by self-assessment on three occasions: (a) prior to the beginning of the competition, (b) 1 month after the competition, and (c) 1 year after the start of the competition.
Results: From pretest to posttest smoking increased by 7.5% in the comparison group, while it decreased by 0.2% in the intervention group (OR = 2.19; P < 0.001). In the follow-up measurement, a clear increase in smoking prevalence occurs in all groups; however, the pupils in the intervention condition still have a significant lower increase of smoking (OR = 1.45; P < 0.01). Moreover, with regard to the nonsmokers at baseline, pupils in the comparison group showed significantly higher prevalences in smoking than the intervention group in the postmeasurement, 7.8 versus 13.9% (OR = 1.98; P < 0.001), as well as in the in the follow-up-measurement, 17 versus 21.3% (OR = 1.36; P < 0.05).
Conclusions: The results suggest that the participation in the competition could delay the onset of smoking in adolescence.