Reducing Cigarette Smoking Among Working Adolescents: Results from the SMART Study

Tobacco cessation interventions for young people

BACKGROUND

Most tobacco control programmes for adolescents are based around prevention of uptake, but teenage smoking is still common. It is unclear if interventions that are effective for adults can also help adolescents to quit. This is the update of a Cochrane Review first published in 2006.

OBJECTIVES

To evaluate the effectiveness of strategies that help young people to stop smoking tobacco.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group's Specialized Register in June 2017. This includes reports for trials identified in CENTRAL, MEDLINE, Embase and PsyclNFO.

SELECTION CRITERIA

We included individually and cluster-randomized controlled trials recruiting young people, aged under 20 years, who were regular tobacco smokers. We included any interventions for smoking cessation; these could include pharmacotherapy, psycho-social interventions and complex programmes targeting families, schools or communities. We excluded programmes primarily aimed at prevention of uptake. The primary outcome was smoking status after at least six months' follow-up among those who smoked at baseline.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of candidate trials and extracted data. We evaluated included studies for risk of bias using standard Cochrane methodology and grouped them by intervention type and by the theoretical basis of the intervention. Where meta-analysis was appropriate, we estimated pooled risk ratios using a Mantel-Haenszel fixed-effect method, based on the quit rates at six months' follow-up.

MAIN RESULTS

Forty-one trials involving more than 13,000 young people met our inclusion criteria (26 individually randomized controlled trials and 15 cluster-randomized trials). We judged the majority of studies to be at high or unclear risk of bias in at least one domain. Interventions were varied, with the majority adopting forms of individual or group counselling, with or without additional self-help materials to form complex interventions. Eight studies used primarily computer or messaging interventions, and four small studies used pharmacological interventions (nicotine patch or gum, or bupropion). There was evidence of an intervention effect for group counselling (9 studies, risk ratio (RR) 1.35, 95% confidence interval (CI) 1.03 to 1.77), but not for individual counselling (7 studies, RR 1.07, 95% CI 0.83 to 1.39), mixed delivery methods (8 studies, RR 1.26, 95% CI 0.95 to 1.66) or the computer or messaging interventions (pooled RRs between 0.79 and 1.18, 9 studies in total). There was no clear evidence for the effectiveness of pharmacological interventions, although confidence intervals were wide (nicotine replacement therapy 3 studies, RR 1.11, 95% CI 0.48 to 2.58; bupropion 1 study RR 1.49, 95% CI 0.55 to 4.02). No subgroup precluded the possibility of a clinically important effect. Studies of pharmacotherapies reported some adverse events considered related to study treatment, though most were mild, whereas no adverse events were reported in studies of behavioural interventions. Our certainty in the findings for all comparisons is low or very low, mainly because of the clinical heterogeneity of the interventions, imprecision in the effect size estimates, and issues with risk of bias.

AUTHORS' CONCLUSIONS

There is limited evidence that either behavioural support or smoking cessation medication increases the proportion of young people that stop smoking in the long-term. Findings are most promising for group-based behavioural interventions, but evidence remains limited for all intervention types. There continues to be a need for well-designed, adequately powered, randomized controlled trials of interventions for this population of smokers.

Workplace interventions for smoking cessation

BACKGROUND

The workplace has potential as a setting through which large groups of people can be reached to encourage smoking cessation.

OBJECTIVES

1. To categorize workplace interventions for smoking cessation tested in controlled studies and to determine the extent to which they help workers to stop smoking.2. To collect and evaluate data on costs and cost effectiveness associated with workplace interventions.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group Specialized Register (July 2013), MEDLINE (1966 - July 2013), EMBASE (1985 - June 2013), and PsycINFO (to June 2013), amongst others. We searched abstracts from international conferences on tobacco and the bibliographies of identified studies and reviews for additional references.

SELECTION CRITERIA

We selected interventions conducted in the workplace to promote smoking cessation. We included only randomized and quasi-randomized controlled trials allocating individuals, workplaces, or companies to intervention or control conditions.

DATA COLLECTION AND ANALYSIS

One author extracted information relating to the characteristics and content of all kinds of interventions, participants, outcomes and methods of the studies, and a second author checked them. For this update we have conducted meta-analyses of the main interventions, using the generic inverse variance method to generate odds ratios and 95% confidence intervals.

MAIN RESULTS

We include 57 studies (61 comparisons) in this updated review. We found 31 studies of workplace interventions aimed at individual workers, covering group therapy, individual counselling, self-help materials, nicotine replacement therapy, and social support, and 30 studies testing interventions applied to the workplace as a whole, i.e. environmental cues, incentives, and comprehensive programmes. The trials were generally of moderate to high quality, with results that were consistent with those found in other settings. Group therapy programmes (odds ratio (OR) for cessation 1.71, 95% confidence interval (CI) 1.05 to 2.80; eight trials, 1309 participants), individual counselling (OR 1.96, 95% CI 1.51 to 2.54; eight trials, 3516 participants), pharmacotherapies (OR 1.98, 95% CI 1.26 to 3.11; five trials, 1092 participants), and multiple intervention programmes aimed mainly or solely at smoking cessation (OR 1.55, 95% CI 1.13 to 2.13; six trials, 5018 participants) all increased cessation rates in comparison to no treatment or minimal intervention controls. Self-help materials were less effective (OR 1.16, 95% CI 0.74 to 1.82; six trials, 1906 participants), and two relapse prevention programmes (484 participants) did not help to sustain long-term abstinence. Incentives did not appear to improve the odds of quitting, apart from one study which found a sustained positive benefit. There was a lack of evidence that comprehensive programmes targeting multiple risk factors reduced the prevalence of smoking.

AUTHORS' CONCLUSIONS

1. We found strong evidence that some interventions directed towards individual smokers increase the likelihood of quitting smoking. These include individual and group counselling, pharmacological treatment to overcome nicotine addiction, and multiple interventions targeting smoking cessation as the primary or only outcome. All these interventions show similar effects whether offered in the workplace or elsewhere. Self-help interventions and social support are less effective. Although people taking up these interventions are more likely to stop, the absolute numbers who quit are low.2. We failed to detect an effect of comprehensive programmes targeting multiple risk factors in reducing the prevalence of smoking, although this finding was not based on meta-analysed data. 3. There was limited evidence that participation in programmes can be increased by competitions and incentives organized by the employer, although one trial demonstrated a sustained effect of financial rewards for attending a smoking cessation course and for long-term quitting. Further research is needed to establish which components of this trial contributed to the improvement in success rates.4. Further research would be valuable in low-income and developing countries, where high rates of smoking prevail and smoke-free legislation is not widely accepted or enforced.

What is actually measured in process evaluations for worksite health promotion programs: a systematic review

Background

Numerous worksite health promotion program (WHPPs) have been implemented the past years to improve employees’ health and lifestyle (i.e., physical activity, nutrition, smoking, alcohol use and relaxation). Research primarily focused on the effectiveness of these WHPPs. Whereas process evaluations provide essential information necessary to improve large scale implementation across other settings. Therefore, this review aims to: (1) further our understanding of the quality of process evaluations alongside effect evaluations for WHPPs, (2) identify barriers/facilitators affecting implementation, and (3) explore the relationship between effectiveness and the implementation process.

Methods

Pubmed, EMBASE, PsycINFO, and Cochrane (controlled trials) were searched from 2000 to July 2012 for peer-reviewed (randomized) controlled trials published in English reporting on both the effectiveness and the implementation process of a WHPP focusing on physical activity, smoking cessation, alcohol use, healthy diet and/or relaxation at work, targeting employees aged 18-65 years.

Results

Of the 307 effect evaluations identified, twenty-two (7.2%) published an additional process evaluation and were included in this review. The results showed that eight of those studies based their process evaluation on a theoretical framework. The methodological quality of nine process evaluations was good. The most frequently reported process components were dose delivered and dose received. Over 50 different implementation barriers/facilitators were identified. The most frequently reported facilitator was strong management support. Lack of resources was the most frequently reported barrier. Seven studies examined the link between implementation and effectiveness. In general a positive association was found between fidelity, dose and the primary outcome of the program.

Conclusions

Process evaluations are not systematically performed alongside effectiveness studies for WHPPs. The quality of the process evaluations is mostly poor to average, resulting in a lack of systematically measured barriers/facilitators. The narrow focus on implementation makes it difficult to explore the relationship between effectiveness and implementation. Furthermore, the operationalisation of process components varied between studies, indicating a need for consensus about defining and operationalising process components.

Tobacco cessation interventions for young people

BACKGROUND

Most tobacco control programmes for adolescents are based around prevention of uptake, but teenage smoking is still common. It is unclear if interventions that are effective for adults can also help adolescents to quit. This is the second update of a Cochrane review first published in 2006.

OBJECTIVES

To evaluate the effectiveness of strategies that help young people to stop smoking tobacco.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group's Specialized Register in February 2013. This includes reports for trials identified in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and PsyclNFO.

SELECTION CRITERIA

We included randomized controlled trials, cluster-randomized controlled trials and other controlled trials recruiting young people, aged less than 20, who were regular tobacco smokers. We included any interventions; these could include pharmacotherapy, psycho-social interventions and complex programmes targeting families, schools or communities. We excluded programmes primarily aimed at prevention of uptake. The primary outcome was smoking status after at least six months follow-up among those who smoked at baseline.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed the eligibility of candidate trials and extracted data. Included studies were evaluated for risk of bias using standard Cochrane methodology. Where meta-analysis was appropriate, we estimated pooled risk ratios using a Mantel-Haenszel fixed-effect method, based on the quit rates at longest follow-up.

MAIN RESULTS

Twenty-eight trials involving approximately 6000 young people met our inclusion criteria (12 cluster-randomized controlled trials, 14 randomized controlled trials and 2 controlled trials). The majority of studies were judged to be at high or unclear risk of bias in at least one domain. Many studies combined components from various theoretical backgrounds to form complex interventions.The majority used some form of motivational enhancement combined with psychological support such as cognitive behavioural therapy (CBT) and some were tailored to stage of change using the transtheoretical model (TTM). Three trials based mainly on TTM interventions achieved moderate long-term success, with a pooled risk ratio (RR) of 1.56 at one year (95% confidence interval (CI) 1.21 to 2.01). The 12 trials that included some form of motivational enhancement gave an estimated RR of 1.60 (95% CI 1.28 to 2.01). None of the 13 individual trials of complex interventions that included cognitive behavioural therapy achieved statistically significant results, and results were not pooled due to clinical heterogeneity. There was a marginally significant effect of pooling six studies of the Not on Tobacco programme (RR of 1.31, 95% CI 1.01 to 1.71), although three of the trials used abstinence for as little as 24 hours at six months as the cessation outcome. A small trial testing nicotine replacement therapy did not detect a statistically significant effect. Two trials of bupropion, one testing two doses and one testing it as an adjunct to NRT, did not detect significant effects. Studies of pharmacotherapies reported some adverse events considered related to study treatment, though most were mild, whereas no adverse events were reported in studies of behavioural interventions.

AUTHORS' CONCLUSIONS

Complex approaches show promise, with some persistence of abstinence (30 days point prevalence abstinence or continuous abstinence at six months), especially those incorporating elements sensitive to stage of change and using motivational enhancement and CBT. Given the episodic nature of adolescent smoking, more data is needed on sustained quitting. There were few trials with evidence about pharmacological interventions (nicotine replacement and bupropion), and none demonstrated effectiveness for adolescent smokers. There is not yet sufficient evidence to recommend widespread implementation of any one model. There continues to be a need for well-designed adequately powered randomized controlled trials of interventions for this population of smokers.

A framework to prevent and control tobacco among adolescents and children: introducing the IMPACT model

The objective of this paper is to provide a comprehensive evidence based model aimed at addressing multi-level risk factors influencing tobacco use among children and adolescents with multi-level policy and programmatic approaches in India. Evidences around effectiveness of policy and program interventions from developed and developing countries were reviewed using Pubmed, Scopus, Google Scholar and Ovid databases. This evidence was then categorized under three broad approaches: Policy level approaches (increased taxation on tobacco products, smoke-free laws in public places and work places, effective health warnings, prohibiting tobacco advertising, promotions and sponsorships, and restricting access to minors); Community level approaches (school health programs, mass media campaigns, community based interventions, promoting tobacco free norms) and Individual level approaches (promoting cessation in various settings). This review of literature around determinants and interventions was organized into developing the IMPACT framework. The paper further presents a comparative analysis of tobacco control interventions in India vis a vis the proposed approaches. Mixed results were found for prevention and control efforts targeting youth. However, this article suggests a number of intervention strategies that have shown to be effective. Implementing these interventions in a coordinated way will provide potential synergies across interventions. Pediatricians have prominent role in advocating and implementing the IMPACT framework in countries aiming to prevent and control tobacco use among adolescents and children.

Smoking cessation for adolescents: a review of pharmacological and psychosocial treatments

Unlike the vast literature on smoking cessation in adults, research in adolescents has gained significant attention only within the last decade. Even with this increase in focus, research into pharmacological aids for smoking cessation in adolescents (e.g., nicotine replacement therapy, bupropion) is a more recent phenomenon and has produced only modest results. While more extensive, much of the research on behaviorally- or psychosocially-based adolescent smoking cessation interventions has been limited by a lack of control for contact time, biochemical verification of self-reported abstinence, and/or a theoretical focus for the interventions. The MEDLINE, PubMed, PSYCInfo, EMBASE, ERIC, CINHAL, Cochrane CENTRAL and Systematic Review databases were searched for articles relevant to adolescent smoking cessation treatment. After briefly examining the adolescent smoking cessation research prior to 2000, more recent developments in pharmacological aids and psychological treatment will be reviewed. Investigations have made progress in elucidating efficacious treatments for adolescent smokers, but much work remains to be done in both pharmacological and non-pharmacological areas of treatment. With the current state of the literature as a guide, future directions for research into smoking cessation for adolescents will be proposed.

Youth tobacco use cessation: 2008 update

In this paper, an empirical review of 64 teen tobacco use cessation studies is provided. Examined include program contents, delivery modalities, number of contacts, and expected quit rates. In addition, means of recruitment and retention of smokers in programming are discussed. Also, promising contemporary methods of teen smoking cessation are examined, including use of pharmacologic adjuncts, electronic technology, and cigarette price increases (and no smoking policy). Conclusions are made regarding implications for developing and implementing teen tobacco use cessation programs.

Therapy for specific problems: youth tobacco cessation

Cigarette smoking is the leading cause of premature morbidity and mortality in the United States. The majority of children smoke their first cigarette in early adolescence, and many older teens have well-established dependence on nicotine. Efforts to promote and support smoking cessation among these youth smokers are critical. The available experimental studies of youth cessation interventions find that behavioral interventions increase the chances of youth smokers achieving successful cessation. Currently there is insufficient evidence for the effectiveness of pharmacological treatments with youth smokers. Many innovative studies have been compromised by challenges in recruiting sufficient numbers of youth, obtaining approval for waivers of parental consent, and high attrition in longitudinal studies. Key areas for future work include bridging the fields of adolescent development and treatment design, matching treatments to developmental trajectories of smoking behavior, better understanding treatment processes and treatment moderators, and building demand for evidence-based cessation treatments.

Workplace interventions for smoking cessation

BACKGROUND

The workplace has potential as a setting through which large groups of people can be reached to encourage smoking cessation.

OBJECTIVES

To categorize workplace interventions for smoking cessation tested in controlled studies and to determine the extent to which they help workers to stop smoking or to reduce tobacco consumption.

SEARCH STRATEGY

We searched the Cochrane Tobacco Addiction Group Specialized Register in April 2008, MEDLINE (1966 - April 2008), EMBASE (1985 - Feb 2008) and PsycINFO (to March 2008). We searched abstracts from international conferences on tobacco and the bibliographies of identified studies and reviews for additional references.

SELECTION CRITERIA

We selected interventions conducted in the workplace to promote smoking cessation. We included only randomized and quasi-randomized controlled trials allocating individuals, workplaces or companies to intervention or control conditions.

DATA COLLECTION AND ANALYSIS

Information relating to the characteristics and content of all kinds of interventions, participants, outcomes and methods of the study was abstracted by one author and checked by another. Because of heterogeneity in the design and content of the included studies, we did not attempt formal meta-analysis, and evaluated the studies using qualitative narrative synthesis.

MAIN RESULTS

We include 51 studies covering 53 interventions in this updated review. We found 37 studies of workplace interventions aimed at individual workers, covering group therapy, individual counselling, self-help materials, nicotine replacement therapy and social support. The results were consistent with those found in other settings. Group programmes, individual counselling and nicotine replacement therapy increased cessation rates in comparison to no treatment or minimal intervention controls. Self-help materials were less effective. We also found 16 studies testing interventions applied to the workplace as a whole. There was a lack of evidence that comprehensive programmes reduced the prevalence of smoking. Incentive schemes increased attempts to stop smoking, though there was less evidence that they increased the rate of actual quitting.

AUTHORS' CONCLUSIONS

1. We found strong evidence that interventions directed towards individual smokers increase the likelihood of quitting smoking. These include individual and group counselling and pharmacological treatment to overcome nicotine addiction. All these interventions show similar effects whether offered in the workplace or elsewhere. Self-help interventions and social support are less effective. Although people taking up these interventions are more likely to stop, the absolute numbers who quit are low.2. There was limited evidence that participation in programmes can be increased by competitions and incentives organized by the employer.3. We failed to detect an effect of comprehensive programmes in reducing the prevalence of smoking.

Design and analysis of group-randomized trials in cancer: a review of current practices

BACKGROUND

Previous reviews have identified problems in the design and analysis of group-randomized trials in a number of areas. Similar problems may exist in cancer research, but there have been no comprehensive reviews.

METHODS

We searched Medline and PubMed for group-randomized trials focused on cancer prevention and control that were published between 2002 and 2006. We located and reviewed 75 articles to determine whether articles included evidence of taking group randomization into account in establishing the size of the trial, such as reporting the expected intraclass correlation, the group component of variance, or the variance inflation factor. We also examined the analytical approaches to determine their appropriateness.

RESULTS

Only 18 (24%) of the 75 articles documented appropriate methods for sample size calculations. Only 34 (45%) limited their reports to analyses judged to be appropriate. Fully 26 (34%) failed to report any analyses that were judged to be appropriate. The most commonly used inappropriate analysis was an analysis at the individual level that ignored the groups altogether. Nine articles (12%) did not provide sufficient information.

CONCLUSIONS

Many investigators who use group-randomized trials in cancer research do not adequately attend to the special design and analytic challenges associated with these trials. Failure to do so can lead to reporting type I errors as real effects, mislead investigators and policy-makers, and slow progress toward control and prevention of cancer. A collaborative effort by investigators, statisticians, and others will be required to ensure that group-randomized trials are planned and analyzed using appropriate methods so that the scientific community can have confidence in the published results.

Revue systématique d’essais comparatifs randomisés d’interventions d’abandon du tabac chez les jeunes

Contexte : Bien que l’usage de la cigarette demeure courant parmi les jeunes, on en sait encore bien peu sur la façon de les aider à cesser de fumer. Seulement quelques revues systématiques d’essais comparatifs randomisés (ECR) ont évalué l’efficacité des interventions d’abandon du tabac chez les jeunes.

Objectif : Résumer les connaissances sur l’efficacité des interventions visant à aider les jeunes à cesser de fumer en se basant sur des données probantes provenant d’ECR.

Sélection des études et extraction des données : Nous avons retenu tous les ECR publiés qui évaluaient les interventions d’abandon du tabac ciblant les jeunes âgés de 20 ans et moins et qui rapportaient l’abstinence au tabac selon une analyse en intention de traiter. Nous avons relevé les études pertinentes provenant de huit revues de synthèse décrivant des études portant sur des interventions d’abandon du tabac publiées entre 2002 et 2006, ainsi qu’une recherche menée dans les bases de données PubMed et PsycINFO entre 2001 et novembre  2006. Nous rapportons l’abstinence au tabagisme au moment du suivi le plus prolongé. Les auteurs ont sélectionné d’un commun accord les données retenues pour cette revue.

Résultats : Nous avons identifié 16 ECR auxquels ont participé 6 623 jeunes ; 11 études évaluant des interventions comportementales qui comprenaient 5 764 participants; quatre examinant des interventions pharmacologiques qui comptaient 529 participants ; et une se penchant sur l’acupuncture au laser qui comportait 330 participants. Trois interventions comportementales menées en milieu scolaire sur quatre et une intervention réalisée en milieu de soins de santé sur quatre ont fait augmenter de façon significative l’abstinence au tabac, quatre semaines à 24 mois suivant les interventions. Parmi les quatre ERC qui évaluaient les interventions pharmacologiques réalisées à l’aide soit de bupropion, de timbres ou de gommes à la nicotine, une étude, où le timbre à la nicotine a été utilisé en combinaison avec un counseling cognitivo-comportemental, a montré une hausse marquée, quoique non significative, de l’abstinence six mois après la date d’abandon.

Conclusion : Il existe encore peu de preuves démontrant l’efficacité des interventions d’abandon du tabac chez les jeunes. Quatre programmes en milieu scolaire et une intervention dans un établissement de santé ont mis en évidence une certaine efficacité, tandis que pour la thérapie pharmacologique, les résultats ne sont pas encore concluants.

Tobacco cessation interventions for young people

BACKGROUND

Teenage smoking prevalence is around 15% in developing countries (with wide variation from country to country), and around 26% in the UK and USA. Although most tobacco control programmes for adolescents are based around prevention of uptake, there are also a number of initiatives to help those who want to quit. Since those who do not smoke before the age of 20 are significantly less likely to start as adults, there is a strong case for programmes for young people that address both prevention and treatment.

OBJECTIVES

To evaluate the effectiveness of strategies that help young people to stop smoking tobacco.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Tobacco Addiction Group's Specialized Register, MEDLINE, EMBASE, PsyclNFO, ERIC, CINAHL, and the bibliographies of identified trials. We also searched the 'grey' literature (unpublished materials), and contacted authors and experts in the field where necessary.

SELECTION CRITERIA

Types of studies: Randomized controlled trials, cluster-randomized controlled trials and controlled trials.

TYPES OF PARTICIPANTS

Young people, aged less than 20, who are regular tobacco smokers. Types of interventions: The interventions ranged from simple ones such as pharmacotherapy, targeting individual young people, through complex programmes targeting people or organizations associated with young people (for example, their families or schools), or the community in which young people live. We included cessation programmes but excluded programmes primarily aimed at prevention of uptake. Types of outcome measures: The primary outcome was smoking status at six months follow up, among those who smoked at baseline. We report the definition of cessation used in each trial (e.g seven- or thirty-day point prevalence abstinence, or sustained or prolonged abstinence), and we preferred biochemically verified cessation when that measure was available.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed the eligibility of candidate trials identified by the searches, and extracted data from them. We categorized included trials as being at low, medium or high risk of bias, based on concealment of allocation, blinding (where applicable) and the handling of attrition and losses to follow up. We conducted limited meta-analyses of some of the trials, provided that it was appropriate to group them and provided that there was minimal heterogeneity between them. We estimated pooled odds ratios using the Mantel-Haenszel method, based on the quit rates at longest follow up for trials with at least six months follow up from the start of the intervention.

MAIN RESULTS

We found 15 trials, covering 3605 young people, which met our inclusion criteria (seven cluster-randomized controlled trials, six randomized controlled trials and two controlled trials). Three trials used or tested the transtheoretical model (stages of change) approach, two tested pharmacological aids to quitting (nicotine replacement and bupropion), and the remaining trials used various psycho-social interventions, such as motivational enhancement or behavioural management. The trials evaluating TTM interventions achieved moderate long-term success, with a pooled odds ratio (OR) at one year of 1.70 ( 95% confidence interval (CI) 1.25 to 2.33) persisting at two-year follow up with an OR of 1.38 (95% CI 0.99 to 1.92). Neither of the pharmacological intervention trials achieved statistically significant results (data not pooled), but both were small-scale, with low power to detect an effect. The three interventions (5 trials) which used cognitive behavioural therapy interventions did not individually achieve statistically significant results, although when the three Not on Tobacco trials were pooled the OR 1.87; (95% CI 1.00 to 3.50) suggested some measure of effectiveness. Although the three trials that incorporated motivational interviewing as a component of the intervention achieved a pooled OR of 2.05 (95% CI 1.10 to 3.80), the impossibility of isolating the effect of the motivational interviewing in these trials meant that we could not draw meaningful inferences from that analysis.

AUTHORS' CONCLUSIONS

Complex approaches show promise, with some persistence of abstinence (30 days point prevalence abstinence at six months), especially those incorporating elements sensitive to stage of change. There were few trials with evidence about pharmacological interventions (nicotine replacement and bupropion), and none demonstrated effectiveness for adolescent smokers. Psycho-social interventions have not so far demonstrated effectiveness, although pooled results for the Not on Tobacco trials suggest that that this approach may yet prove to be effective; however, their definition of cessation (one or more smoke-free days) may not adequately account for the episodic nature of much adolescent smoking. There is a need for well-designed adequately powered randomized controlled trials for this population of smokers, with a minimum of six months follow up and rigorous definitions of cessation (sustained and biochemically verified). Attrition and losses to follow up are particularly problematic in trials for young smokers, and need to be kept to a minimum, so that management and interpretation of missing data need not compromise the findings.