An informal school-based peer-led intervention for smoking prevention in adolescence (ASSIST): a cluster randomised trial

Abstract

SummaryBackgroundSchools in many countries undertake programmes for smoking prevention, but systematic reviews have shown mixed evidence of their effectiveness. Most peer-led approaches have been classroom-based, and rigorous assessments are scarce. We assessed the effectiveness of a peer-led intervention that aimed to prevent smoking uptake in secondary schools.MethodsWe undertook a cluster randomised controlled trial of 10 730 students aged 12–13 years in 59 schools in England and Wales. 29 schools (5372 students) were randomly assigned by stratified block randomisation to the control group to continue their usual smoking education and 30 (5358 students) to the intervention group. The intervention (ASSIST [A Stop Smoking In Schools Trial] programme) consisted of 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.FindingsThe odds ratio of being a smoker in intervention compared with control schools was 0·75 (95% CI 0·55–1·01) immediately after the intervention (n=9349 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=8756). 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=3483]), and 0·85 (0·70–1·02 [n=3294]), 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).InterpretationThe 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.FundingMRC (UK).

Peer‐led interventions to prevent tobacco, alcohol and/or drug use among young people aged 11–21 years: a systematic review and meta‐analysis

“…Approximately half of the studies (n=9 of 17, 52%) targeted tobacco smoking and most were conducted in the United States . The remaining studies were conducted in the United Kingdom 19, Australia 35, Norway 39, Spain 36, Poland and Romania 54, while a multi‐centre study was conducted in Australia , Norway , Chile and Swaziland 51. A number of studies targeted young people aged 12–13 years ( n  = 8), while four studies targeted young people aged 13–18 and most were conducted in the school setting.…”

“…In eight studies 19, 20, 33, 34, 35, 37, 39, 52, peers of a similar age were nominated by their classmates, while in four studies, older‐age peers were selected by staff or researchers 32, 36, 51, 53. In other programmes, PLs either volunteered 31, 36, 38 or the age or method of selection was unclear.…”

“…Among those interventions that were the most effective 19, 20, 31, 54, however, there was no clear pattern of factors associated with impact, such as shared intervention domains, duration of intervention or underlying theory. In addition, no clear message emerged regarding whether peers, teachers or professionals were more effective at instigating behaviour change.…”

“…For the latter adjustments, the intracluster correlation coefficient (ICC) reported by Campbell et al . 19 was used (see Supporting information, Material S2). These assumptions were examined in sensitivity analyses.…”

“…To date, peer‐based programmes have been employed to target substance use, sexual risk behaviour, HIV prevention and psychosocial wellbeing among young people 19, 20, 21, 22, 23, 24, 25, and there is promising evidence from existing intervention models 19, 22, 26. Earlier systematic reviews suggested that there was evidence that peer interventions could change behaviour, as well as improve knowledge 18, 27, 28.…”