Effect of a peer-led prevention program (P2P) on smoking in vocational high school students: Results from a two-school-year cluster-randomized trial.

Aims: The aim of this work was to measure the impact of P2P (i.e. peer-to-peer), a peer-led smoking prevention intervention, on daily smoking prevalence of adolescents over 2 school years.

Design: A cluster-randomized controlled trial was performed over a 16-month follow-up (trial status: closed to follow-up). P2P was implemented 1-3 and 13-15 months after baseline. Assessments took place at baseline and 4, 10 and 16 months after baseline. The research team, assessors and adolescents were blinded to the study-arm assignment only at baseline.

Setting: Fifteen vocational high schools in France were randomized into two clusters, using a 1:1 allocation ratio per French department (n intervention = 7, n control = 8).

Participants: Participants comprised a sample of 2010 students in year 11 (i.e. 15-16 years) in vocational high schools. A total of 437 students could not be assessed at baseline (absent or left school), yielding a total sample of 1573 students (n intervention = 749, n control = 824).

Intervention And Comparator: The P2P programme trained voluntary students to become peer educators and design smoking prevention actions for their schoolmates in the intervention group (n = 945 students), compared with a passive control group (n = 1065 students).

Measurements: The primary outcome was change from baseline in the prevalence of self-reported daily smoking (i.e. at least one cigarette per day) at 16 months.

Findings: The 'time × group' interaction indicated that, compared with the control group, the intervention group had statistically significantly fewer daily smokers after 16 months [odds ratio (OR) = 0.33, 95% confidence interval (CI) = 0.20, 0.53]. Similarly, compared with the control group, the intervention group had statistically significantly fewer daily smokers after 4 months (OR = 0.50, 95% CI = 0.30, 0.82) and 10 months (OR = 0.60, 95% CI = 0.37, 0.98). No adverse events of P2P2 were reported.

Conclusions: A cluster-randomized trial found evidence that the peer-led P2P (peer-to-peer) smoking prevention intervention reduced the uptake of daily smoking among high school students in France over 16 months.