The effect of two elementary school-based prevention interventions on being offered tobacco and the transition to smoking

Polygenic Score × Intervention Moderation: an Application of Discrete-Time Survival Analysis to Model the Timing of First Marijuana Use Among Urban Youth

The present study examines the interaction between a polygenic score and an elementary school-based universal preventive intervention trial and its effects on a discrete-time survival analysis of time to first smoking marijuana. Research has suggested that initiation of substances is both genetically and environmentally driven (Rhee et al., Archives of general psychiatry 60:1256-1264, 2003; Verweij et al., Addiction 105:417-430, 2010). A previous work has found a significant interaction between the polygenic score and the same elementary school-based intervention with tobacco smoking (Musci et al., in press). The polygenic score reflects the contribution of multiple genes and has been shown in prior research to be predictive of smoking cessation, tobacco use, and marijuana use (Uhl et al., Molecular Psychiatry 19:50-54, 2014). Using data from a longitudinal preventive intervention study (N = 678), we examined age of first marijuana use from sixth grade to age 18. Genetic data were collected during emerging adulthood and were genotyped using the Affymetrix 6.0 microarray (N = 545). The polygenic score was computed using these data. Discrete-time survival analysis was employed to test for intervention main and interaction effects with the polygenic score. We found main effect of the polygenic score approaching significance, with the participants with higher polygenic scores reporting their first smoking marijuana at an age significantly later than controls (p = .050). We also found a significant intervention × polygenic score interaction effect at p = .003, with participants at the higher end of the polygenic score benefiting the most from the intervention in terms of delayed age of first use. These results suggest that genetics may play an important role in the age of first use of marijuana and that differences in genetics may account for the differential effectiveness of classroom-based interventions in delaying substance use experimentation.

Modelling opportunity: An examination of quadratic effects of adolescent Venezuelan substance use

INTRODUCTION AND AIMS

Numerous studies have found a linear relationship between an exposure opportunity and age of first drug use. This study further tests this relationship by exploring whether a quadratic exposure opportunity best fits the data on age of first use and whether gender moderates this relationship. That is, is there a peak age in which the transition to use occurs for male compared to female adolescents?

DESIGN AND METHODS

A sample of 1716 adolescents from 14 public and private schools, representative of two school districts in Caracas, Venezuela, was examined using a zero-inflated Poisson modelling approach to test for quadratic effects. A series of models were tested for each set of substances (alcohol, tobacco and other drugs) to assess whether a quadratic model has better predictive ability than linear models and to test whether gender moderates the quadratic relationship.

RESULTS

After controlling for common covariates, the quadratic models for alcohol indicated the peak age of transition from an exposure opportunity to use was 10-years of age in this Venezuelan sample. Gender did not moderate these models suggesting an important move toward gender equality in substance use.

DISCUSSION AND CONCLUSIONS

Focused efforts on preventing exposure to alcohol use during these windows of rapid transition is likely to have the greatest impact on delaying age of onset, which will reduce the overall prevalence of alcohol related problems among adolescents.

Family-focussed interventions to reduce harm from smoking in primary school-aged children: A systematic review of evaluative studies

Children living in families where adults smoke are exposed to harmful effects of tobacco smoke and risk a predisposition to smoking initiation. Interventions to support families to reduce risk of harm from smoking have been developed and tested. The purpose of this review is to identify effective family-based interventions used to promote smoke-free home environments in families with primary school age children (aged 5-12years). A systematic search of MEDLINE, Cochrane and CINAHL electronic databases was conducted. Narrative synthesis of included articles was completed. Guidelines for reporting behaviour change interventions were used to summarise and compare intervention timing, content, intensity and delivery. Quality of included studies was critiqued using United States Preventative Services Taskforce (USPST) procedures for internal and external validity. Narrative synthesis was based on methods described by Popay and colleagues. Nineteen articles that evaluated 14 intervention studies focussed on child smoking prevention (n=5), parent smoking cessation (n=4) and environmental tobacco smoke reduction (n=6). Interventions and outcomes were heterogeneous, and were rarely informed by theoretical frameworks relating to family, parenting or child development. Family based interventions may be an important strategy to reduce the effects of smoking for children. There is a need for interventions to be informed by theory relevant to children, parenting and families.

Systematic review of universal school-based 'resilience' interventions targeting adolescent tobacco, alcohol or illicit substance use: A meta-analysis

Universal school-based interventions that address adolescent 'resilience' may represent a means of reducing adolescent substance use, however previous systematic reviews have not examined the effectiveness of such an intervention approach. A systematic review was undertaken to 1) assess whether universal school-based 'resilience' interventions are effective in reducing the prevalence of tobacco, alcohol or illicit substance use by adolescents, and 2) describe such effectiveness per intervention characteristic subgroups. Eligible studies were peer-reviewed reports (1994-2015) of randomised controlled trials including participants aged 5-18years that reported adolescent tobacco, alcohol or illicit substance use, and implemented a universal school-based 'resilience' intervention (i.e. those addressing both individual (e.g. self-esteem) and environmental (e.g. school connectedness) protective factors of resilience). Trial effects for binary outcomes were synthesised via meta-analyses and effect sizes reported as odds ratios. Subgroup (by intervention type, prevention approach, setting, intervention duration, follow-up length) and sensitivity analyses (excluding studies at high risk of bias) were conducted. Nineteen eligible studies were identified from 16,619 records (tobacco: n=15, alcohol: n=17, illicit: n=11). An overall intervention effect was found for binary measures of illicit substance use (n=10; OR: 0.78, 95%CI: 0.6-0.93, p=0.007,Tau²=0.0, I²=0%), but not tobacco or alcohol use. A similar result was found when studies assessed as high risk of bias were excluded. Overall intervention effects were evident for illicit substance use within multiple intervention characteristic subgroups, but not tobacco and alcohol. Such results support the implementation of universal school-based interventions that address 'resilience' protective factors to reduce adolescent illicit substance use, however suggest alternate approaches are required for tobacco and alcohol use. PROSPERO registration: CRD42014004906.

Developmental Patterns of Adolescent Marijuana and Alcohol Use and Their Joint Association with Sexual Risk Behavior and Outcomes in Young Adulthood

Urban populations disproportionately experience poor sexual outcomes, including high rates of teenage pregnancy and sexually transmitted infections. However, the contribution of substance use across adolescence to poor sexual outcomes in young adulthood has not been investigated in depth, despite offering opportunities for more targeted prevention. This study aimed to estimate joint trajectories of adolescent alcohol and marijuana use to determine if they relate differently to four sexual outcomes: multiple sexual partners, sex without a condom, teenage pregnancy, and contraction of a sexually transmitted infection in young adulthood (by age 25). Data came from a longitudinal study of urban youth followed from age 6 to age 25, with annual assessments during adolescence and young adulthood (n = 608). The sample showed high levels of sexual risk, with young adults on average having sex without a condom once in the past month, 28.5% having multiple sexual partners in the past month, one quarter having contracted a sexually transmitted infection, and over 60% of the women being pregnant as a teenager and 36% of the men having gotten a partner pregnant. Applying longitudinal latent profile analysis to estimate joint trajectories of alcohol and marijuana use from grades 8-12, we identified four classes representing high dual use, moderate alcohol use, moderate alcohol use with increasing marijuana use, and non-use. Class membership differently predicted all four outcomes investigated with high dual users having the highest level of teenage pregnancy and the increasing marijuana trajectory having the highest risk of engaging with multiple sexual partners in the past month. Results suggest implications for both sexual risk and substance use prevention for urban youth.

Family-Based Interventions in Preventing Children and Adolescents from Using Tobacco: A Systematic Review and Meta-Analysis

BACKGROUND

Tobacco is the main preventable cause of death and disease worldwide. Adolescent smoking is increasing in many countries with poorer countries following the earlier experiences of affluent countries. Preventing adolescents from starting smoking is crucial to decreasing tobacco-related illness.

OBJECTIVE

To assess effectiveness of family-based interventions alone and combined with school-based interventions to prevent children and adolescents from initiating tobacco use.

DATA SOURCES

Fourteen bibliographic databases and the Internet, journals hand-searched, and experts consulted.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

Randomized controlled trials (RCTs) with children or adolescents and families, interventions to prevent starting tobacco use, and follow-up ≥6 months.

STUDY APPRAISAL/SYNTHESIS METHODS

Abstracts/titles independently assessed and data independently entered by 2 authors. Risk of bias was assessed with the Cochrane Risk-of-Bias tool.

RESULTS

Twenty-seven RCTs were included. Nine trials of never-smokers compared with a control provided data for meta-analysis. Family intervention trials had significantly fewer students who started smoking. Meta-analysis of 2 RCTs of combined family and school interventions compared with school only, showed additional significant benefit. The common feature of effective high-intensity interventions was encouraging authoritative parenting.

LIMITATIONS

Only 14 RCTs provided data for meta-analysis (approximately a third of participants). Of the 13 RCTs that did not provide data for meta-analysis 8 compared a family intervention with no intervention and 1 reported significant effects, and 5 compared a family combined with school intervention with a school intervention only and none reported additional significant effects.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

There is moderate-quality evidence that family-based interventions prevent children and adolescents from starting to smoke.

Polygenic score × intervention moderation: an application of discrete-time survival analysis to modeling the timing of first tobacco use among urban youth

The present study examines the interaction between a polygenic score and an elementary school-based universal preventive intervention trial. The polygenic score reflects the contribution of multiple genes and has been shown in prior research to be predictive of smoking cessation and tobacco use (Uhl et al., 2014). Using data from a longitudinal preventive intervention study, we examined age of first tobacco use from sixth grade to age 18. Genetic data were collected during emerging adulthood and were genotyped using the Affymetrix 6.0 microarray. The polygenic score was computed using these data. Discrete-time survival analysis was employed to test for intervention main and interaction effects with the polygenic score. We found a main effect of the intervention, with the intervention participants reporting their first cigarette smoked at an age significantly later than controls. We also found an Intervention × Polygenic Score interaction, with participants at the higher end of the polygenic score benefitting the most from the intervention in terms of delayed age of first use. These results are consistent with Belsky and colleagues' (e.g., Belsky, Bakermans-Kranenburg, & van IJzendoorn, 2007; Belsky & Pleuss, 2009, 2013; Ellis, Boyce, Belsky, Bakermans-Kranenburg, & van IJzendoorn, 2011) differential susceptibility hypothesis and the concept of "for better or worse," wherein the expression of genetic variants are optimally realized in the context of an enriched environment, such as provided by a preventive intervention.

A component-centered meta-analysis of family-based prevention programs for adolescent substance use

Although research has documented the positive effects of family-based prevention programs, the field lacks specific information regarding why these programs are effective. The current study summarized the effects of family-based programs on adolescent substance use using a component-based approach to meta-analysis in which we decomposed programs into a set of key topics or components that were specifically addressed by program curricula (e.g., parental monitoring/behavior management,problem solving, positive family relations, etc.). Components were coded according to the amount of time spent on program services that targeted youth, parents, and the whole family; we also coded effect sizes across studies for each substance-related outcome. Given the nested nature of the data, we used hierarchical linear modeling to link program components (Level 2) with effect sizes (Level 1). The overall effect size across programs was .31, which did not differ by type of substance. Youth-focused components designed to encourage more positive family relationships and a positive orientation toward the future emerged as key factors predicting larger than average effect sizes. Our results suggest that, within the universe of family-based prevention, where components such as parental monitoring/behavior management are almost universal, adding or expanding certain youth-focused components may be able to enhance program efficacy.

The role of neighborhood in urban black adolescent marijuana use

BACKGROUND

The present study examined the influence of neighborhood factors on transitions in marijuana involvement during adolescence in a sample of primarily low-income, urban Black youth.

METHODS

556 Black adolescents were interviewed annually beginning in first grade as part of a longitudinal study. Latent class analysis (LCA) was used to examine stages of marijuana involvement from 6th to 9th grades. The influence of neighborhood disorder, drug activity, violent crime, safety and disadvantage on transitions in marijuana involvement was tested using latent transition analysis (LTA).

RESULTS

There was evidence for three stages of involvement: no involvement, offered, and use and problems. Involvement increased steadily during adolescence with a slightly greater risk to transition from offers to use between 6th and 7th grades. Neighborhood disorder (AOR=1.04, CI=1.00, 1.08), drug activity (AOR=1.12, CI=1.02, 1.22) and disadvantage (AOR=1.44, CI=1.10, 1.92) were associated with the transition from marijuana offers to use and problems. Neighborhood disorder (AOR=1.07, CI=1.02, 1.11), drug activity (AOR=1.19, CI=1.10, 1.29) and violent crime (AOR=1.17, CI=1.03, 1.32) were associated with transitioning rapidly from no involvement to use and problems.

CONCLUSIONS

Understanding how neighborhoods could be organized and provided with supports to discourage marijuana use and promote non-drug using behaviors should be an important goal of any prevention program in low-income, urban Black neighborhoods. Enhancing citizen participation and mobilization to address the social processes of neighborhood disorder has the potential to reduce marijuana involvement in these neighborhoods.

Home-based smoking prevention program Smoke-free Kids on smoking-related cognitions: Secondary outcomes from a cluster randomized controlled trial

OBJECTIVES

The home-based smoking prevention programme 'Smoke-free Kids' did not have an effect on primary outcome smoking initiation. A possible explanation may be that the programme has a delayed effect. The aim of this study was to evaluate the effects on the development of important precursors of smoking: smoking-related cognitions.

METHODS

We used a cluster randomised controlled trial in 9- to 11-year-old children and their mothers. The intervention condition received five activity modules, including a communication sheet for mothers, by mail at four-week intervals. The control condition received a fact-based programme. Secondary outcomes were attitudes, self-efficacy and social norms. Latent growth curves analyses were used to calculate the development of cognitions over time. Subsequently, path modelling was used to estimate the programme effects on the initial level and growth of each cognition.

RESULTS

Analyses were performed on 1398 never-smoking children at baseline. Results showed that for children in the intervention condition, perceived maternal norms increased less strongly as compared to the control condition (β = -.10, p = .03). No effects were found for the other cognitions.

CONCLUSION

Based on the limited effects, we do not assume that the programme will have a delayed effect on smoking behaviour later during adolescence.

Family-based programmes for preventing smoking by children and adolescents

BACKGROUND

There is evidence that family and friends influence children's decisions to smoke.

OBJECTIVES

To assess the effectiveness of interventions to help families stop children starting smoking.

SEARCH METHODS

We searched 14 electronic bibliographic databases, including the Cochrane Tobacco Addiction Group specialized register, MEDLINE, EMBASE, PsycINFO, CINAHL unpublished material, and key articles' reference lists. We performed free-text internet searches and targeted searches of appropriate websites, and hand-searched key journals not available electronically. We consulted authors and experts in the field. The most recent search was 3 April 2014. There were no date or language limitations.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions with children (aged 5-12) or adolescents (aged 13-18) and families to deter tobacco use. The primary outcome was the effect of the intervention on the smoking status of children who reported no use of tobacco at baseline. Included trials had to report outcomes measured at least six months from the start of the intervention.

DATA COLLECTION AND ANALYSIS

We reviewed all potentially relevant citations and retrieved the full text to determine whether the study was an RCT and matched our inclusion criteria. Two authors independently extracted study data for each RCT and assessed them for risk of bias. We pooled risk ratios using a Mantel-Haenszel fixed effect model.

MAIN RESULTS

Twenty-seven RCTs were included. The interventions were very heterogeneous in the components of the family intervention, the other risk behaviours targeted alongside tobacco, the age of children at baseline and the length of follow-up. Two interventions were tested by two RCTs, one was tested by three RCTs and the remaining 20 distinct interventions were tested only by one RCT. Twenty-three interventions were tested in the USA, two in Europe, one in Australia and one in India.The control conditions fell into two main groups: no intervention or usual care; or school-based interventions provided to all participants. These two groups of studies were considered separately.Most studies had a judgement of 'unclear' for at least one risk of bias criteria, so the quality of evidence was downgraded to moderate. Although there was heterogeneity between studies there was little evidence of statistical heterogeneity in the results. We were unable to extract data from all studies in a format that allowed inclusion in a meta-analysis.There was moderate quality evidence family-based interventions had a positive impact on preventing smoking when compared to a no intervention control. Nine studies (4810 participants) reporting smoking uptake amongst baseline non-smokers could be pooled, but eight studies with about 5000 participants could not be pooled because of insufficient data. The pooled estimate detected a significant reduction in smoking behaviour in the intervention arms (risk ratio [RR] 0.76, 95% confidence interval [CI] 0.68 to 0.84). Most of these studies used intensive interventions. Estimates for the medium and low intensity subgroups were similar but confidence intervals were wide. Two studies in which some of the 4487 participants already had smoking experience at baseline did not detect evidence of effect (RR 1.04, 95% CI 0.93 to 1.17).Eight RCTs compared a combined family plus school intervention to a school intervention only. Of the three studies with data, two RCTS with outcomes for 2301 baseline never smokers detected evidence of an effect (RR 0.85, 95% CI 0.75 to 0.96) and one study with data for 1096 participants not restricted to never users at baseline also detected a benefit (RR 0.60, 95% CI 0.38 to 0.94). The other five studies with about 18,500 participants did not report data in a format allowing meta-analysis. One RCT also compared a family intervention to a school 'good behaviour' intervention and did not detect a difference between the two types of programme (RR 1.05, 95% CI 0.80 to 1.38, n = 388).No studies identified any adverse effects of intervention.

AUTHORS' CONCLUSIONS

There is moderate quality evidence to suggest that family-based interventions can have a positive effect on preventing children and adolescents from starting to smoke. There were more studies of high intensity programmes compared to a control group receiving no intervention, than there were for other compairsons. The evidence is therefore strongest for high intensity programmes used independently of school interventions. Programmes typically addressed family functioning, and were introduced when children were between 11 and 14 years old. Based on this moderate quality evidence a family intervention might reduce uptake or experimentation with smoking by between 16 and 32%. However, these findings should be interpreted cautiously because effect estimates could not include data from all studies. Our interpretation is that the common feature of the effective high intensity interventions was encouraging authoritative parenting (which is usually defined as showing strong interest in and care for the adolescent, often with rule setting). This is different from authoritarian parenting (do as I say) or neglectful or unsupervised parenting.

The Smoking Outcome Expectation Scale and Anti-Smoking Self-Efficacy Scale for Early Adolescents: Instrument Development and Validation

Smoking-related outcome expectation and self-efficacy have been found to be associated with adolescent smoking initiation. There is, however, a lack of appropriate instruments to investigate early adolescents' smoking outcome expectations and antismoking self-efficacy. The purpose of this study was to develop and validate the Smoking Outcome Expectation Scale (SOES) and Anti-Smoking Self-Efficacy Scale (ASSES). A total of 232 fifth and sixth graders from four elementary schools in Taiwan participated in the study. Both scales had good content validity, internal consistency, and test-retest reliability. On the basis of exploratory factor analysis, the 6-item SOES with two factors accounted for 54.72% of total variance and the 15-item ASSES with three factors accounted for 56.49% of total variance. The SOES had convergent and discriminant validity and ASSES had convergent validity. The two scales could help school nurses to understand early adolescents' smoking outcome expectation and antismoking self-efficacy and to develop more appropriate antismoking curricula.

The value of using schools as community assets for health

In planning, designing, procuring and ensuring delivery of improved services ('commissioning') for the school age population, the outcomes should be students who are healthy to learn and who learn to be healthy. Intuitively, linking education and health development together within the wider learning environment seems a good start to planning school health. However there has been a shortage of either theoretical models that can span different settings or experimental research that demonstrates improved community health. Is there evidence that the wider learning environment provided in a school is valuable in improving health? An initial scoping exercise identified domains of health where there was a promise of health gain. International literature on school health outcomes using the framework of Asset-Based Community Development (ABCD) has been reviewed. It was found that research on a variety of interventions was relevant to schools as an asset for public health. Effective areas for health gain were identified for local planning and evaluation using this community model. However, none of the studies reviewed was originally designed to test schools as assets and most of the research lacked methodological rigour, especially regarding children in low income countries. The ABCD model could help national governments develop resources for both education and health, but there is a global need to generate better quality evidence. Then people who commission for their local communities can make more effective use of these multifaceted assets to improve health and education outcomes for children.

Long-term effects of a home-based smoking prevention program on smoking initiation: a cluster randomized controlled trial

OBJECTIVE

The aims of the study were to evaluate the long-term effects of a home-based smoking prevention program 'Smoke-free Kids' during preadolescence on smoking initiation during adolescence and to test the potential moderating role of parental smoking, socioeconomic status, and asthma.

METHOD

In 2008, 1478 9-11year old children and their mothers were recruited from 418 elementary schools in the Netherlands. An independent statistician randomly allocated schools to one of the two conditions using a 1:1 ratio (single blind): 728 children in the intervention and 750 in the control condition. The intervention condition received five activity modules, including a communication sheet for mothers, by mail at four-week intervals and one booster module one year after baseline. The control condition received a fact-based intervention only. Intention-to-treat analysis was performed on 1398 non-smoking children at baseline.

RESULTS

In the intervention 10.8% of the children started smoking compared to 12% in the control condition. This difference was non-significant (odds ratio=0.90, 95% confidence interval=0.63-1.27). No moderating effects were found.

CONCLUSION

No effects on smoking initiation after 36months were found. Perhaps, the program was implemented with children that were too young. Programs closer to the age of smoking onset should be tested.

The evaluation of two first-grade preventive interventions on childhood aggression and adolescent marijuana use: a latent transition longitudinal mixture model

Aggressive, disruptive behavior during early childhood has been linked to a number of later negative outcomes, one of them being adolescent marijuana use. This study evaluates the impact of two first-grade universal interventions (classroom-centered and family-school partnership) on the development of aggression in early childhood (grades 1-3) and marijuana use in adolescence (grades 8-12) via a latent transition longitudinal mixture model. For males, despite the significant proximal impact of the classroom-centered intervention on trajectory class membership of early childhood aggression, as well as the significant association between aggression trajectory class membership and marijuana use longitudinal latent class membership, the predicted probabilities of being in the high frequency marijuana use class did not differ significantly by intervention status, though in the expected direction. Associations for females are limited to the proximal impact of the classroom-centered intervention on trajectory class membership of aggression. This study extends the prior work of Petras et al. (Prev Sci 12:300-313, 2011) by considering that aggressive, disruptive behavior during early childhood is linked not only to adolescent aggressive, disruptive behavior (i.e., homotypic continuity) but also to adolescent marijuana use (i.e., heterotypic continuity) and by considering that an early intervention may influence later non-targeted behaviors through these heterotypic developmental pathways. Implications for developmental theories and substance abuse prevention are discussed.

School-based programmes for preventing smoking

BACKGROUND

Helping young people to avoid starting smoking is a widely endorsed public health goal, and schools provide a route to communicate with nearly all young people. School-based interventions have been delivered for close to 40 years.

OBJECTIVES

The primary aim of this review was to determine whether school smoking interventions prevent youth from starting smoking. Our secondary objective was to determine which interventions were most effective. This included evaluating the effects of theoretical approaches; additional booster sessions; programme deliverers; gender effects; and multifocal interventions versus those focused solely on smoking.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Tobacco Addiction Group's Specialised Register, MEDLINE, EMBASE, PsycINFO, ERIC, CINAHL, Health Star, and Dissertation Abstracts for terms relating to school-based smoking cessation programmes. In addition, we screened the bibliographies of articles and ran individual MEDLINE searches for 133 authors who had undertaken randomised controlled trials in this area. The most recent searches were conducted in October 2012.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) where students, classes, schools, or school districts were randomised to intervention arm(s) versus a control group, and followed for at least six months. Participants had to be youth (aged 5 to 18). Interventions could be any curricula used in a school setting to deter tobacco use, and outcome measures could be never smoking, frequency of smoking, number of cigarettes smoked, or smoking indices.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed studies for inclusion, extracted data and assessed risk of bias. Based on the type of outcome, we placed studies into three groups for analysis: Pure Prevention cohorts (Group 1), Change in Smoking Behaviour over time (Group 2) and Point Prevalence of Smoking (Group 3).

MAIN RESULTS

One hundred and thirty-four studies involving 428,293 participants met the inclusion criteria. Some studies provided data for more than one group.Pure Prevention cohorts (Group 1) included 49 studies (N = 142,447). Pooled results at follow-up at one year or less found no overall effect of intervention curricula versus control (odds ratio (OR) 0.94, 95% confidence interval (CI) 0.85 to 1.05). In a subgroup analysis, the combined social competence and social influences curricula (six RCTs) showed a statistically significant effect in preventing the onset of smoking (OR 0.49, 95% CI 0.28 to 0.87; seven arms); whereas significant effects were not detected in programmes involving information only (OR 0.12, 95% CI 0.00 to 14.87; one study), social influences only (OR 1.00, 95% CI 0.88 to 1.13; 25 studies), or multimodal interventions (OR 0.89, 95% CI 0.73 to 1.08; five studies). In contrast, pooled results at longest follow-up showed an overall significant effect favouring the intervention (OR 0.88, 95% CI 0.82 to 0.96). Subgroup analyses detected significant effects in programmes with social competence curricula (OR 0.52, 95% CI 0.30 to 0.88), and the combined social competence and social influences curricula (OR 0.50, 95% CI 0.28 to 0.87), but not in those programmes with information only, social influence only, and multimodal programmes.Change in Smoking Behaviour over time (Group 2) included 15 studies (N = 45,555). At one year or less there was a small but statistically significant effect favouring controls (standardised mean difference (SMD) 0.04, 95% CI 0.02 to 0.06). For follow-up longer than one year there was a statistically nonsignificant effect (SMD 0.02, 95% CI -0.00 to 0.02).Twenty-five studies reported data on the Point Prevalence of Smoking (Group 3), though heterogeneity in this group was too high for data to be pooled.We were unable to analyse data for 49 studies (N = 152,544).Subgroup analyses (Pure Prevention cohorts only) demonstrated that at longest follow-up for all curricula combined, there was a significant effect favouring adult presenters (OR 0.88, 95% CI 0.81 to 0.96). There were no differences between tobacco-only and multifocal interventions. For curricula with booster sessions there was a significant effect only for combined social competence and social influences interventions with follow-up of one year or less (OR 0.50, 95% CI 0.26 to 0.96) and at longest follow-up (OR 0.51, 95% CI 0.27 to 0.96). Limited data on gender differences suggested no overall effect, although one study found an effect of multimodal intervention at one year for male students. Sensitivity analyses for Pure Prevention cohorts and Change in Smoking Behaviour over time outcomes suggested that neither selection nor attrition bias affected the results.

AUTHORS' CONCLUSIONS

Pure Prevention cohorts showed a significant effect at longest follow-up, with an average 12% reduction in starting smoking compared to the control groups. However, no overall effect was detected at one year or less. The combined social competence and social influences interventions showed a significant effect at one year and at longest follow-up. Studies that deployed a social influences programme showed no overall effect at any time point; multimodal interventions and those with an information-only approach were similarly ineffective.Studies reporting Change in Smoking Behaviour over time did not show an overall effect, but at an intervention level there were positive findings for social competence and combined social competence and social influences interventions.

Steppingstone and gateway ideas: a discussion of origins, research challenges, and promising lines of research for the future

In this discussion of contributed papers for the special issue of DAD, the author draws attention to early American laws concerning cannabis and to statements made about the epidemiology of cannabis smoking and other drug use between 1858 and the contemporary scene, with coverage of opium, heroin, tobacco, alcohol, cocaine, kava, and other drugs. He discusses these steppingstone and gateway processes in relation to political environment and in relation to scientific challenges such as uncontrolled confounding. He provides a critique of between-individual research designs, including co-twin and co-sib designs of behavior genetics, as well as imaging research, where uncontrolled confounding often exists. He highlights the epidemiologic case-crossover design and prevention research experiments as potentially valuable approaches in new directions for research on the steppingstone and gateway processes.