Findings and methodology are presented for an evaluation of the effectiveness of a peer-led intervention that aimed to prevent smoking uptake in secondary schools.
The evaluation used a cluster randomized controlled trial of 10,730 students ages 12-13 years old in 59 schools in England and Wales. A total of 29 schools (5,372 students) were randomly assigned by stratified block randomization to the control group to continue their usual smoking education and 30 (5,358 students) to the intervention group. The intervention was ASSIST, a Stop Smoking In Schools Trial program, which involved training influential students to act as peer supporters during informal interactions outside the classroom to encourage their peers not to smoke. Follow-up was immediately after the intervention and at 1 and 2 years. Primary outcomes were smoking in the past week in both the school year group and in a group at high risk of regular smoking uptake, which was identified at baseline as occasional, experimental, or ex-smokers. Analysis was by intention to treat. This study is registered, number ISRCTN55572965. The odds ratio of being a smoker in intervention compared with control schools was 0-75 (95 percent CI 0·55-1·01) immediately after the intervention (n-9,349 students), 0.77 (0.59-0.99) at 1-year follow-up (n=9147), and 0.85 (0.72-1.01) at 2-year follow-up (n=8,756). The corresponding odds ratios for the high-risk group were 0.79 (0.55-1.13 [n=3561]), 0.75 (0.56-0.99, n=3,483), and 0.85 (0.70-1.02 n=3,294), respectively. In a three-tier multilevel model with data from all three follow-ups, the odds of being a smoker in intervention compared with control schools was 0.78 (0.64-0.96). The results suggest that, if implemented on a population basis, the ASSIST intervention could lead to a reduction in adolescent smoking prevalence of public-health importance. 4 tables, 2 figures, and 40 references (publisher abstract modified)