Hefler Marita, Liberato Selma C, Thomas David P
Wellbeing & Preventable Chronic Disease Division, Menzies School of Health Research, Darwin, Australia, NT 0811.
Cochrane Database Syst Rev. 2017 Jun 6;6(6):CD008645. doi: 10.1002/14651858.CD008645.pub3.
Adult smoking usually has its roots in adolescence. If individuals do not take up smoking during this period it is unlikely that they ever will. Further, once smoking becomes established, cessation is challenging; the probability of subsequently quitting is inversely proportional to the age of initiation. One novel approach to reducing the prevalence of youth smoking is the use of incentives.
To assess the effect of incentives on preventing children and adolescents (aged 5 to 18 years) from starting to smoke. It was also our intention to assess, where possible, the dose-response of incentives, the costs of incentive programmes, whether incentives are more or less effective in combination with other interventions to prevent smoking initiation, and any unintended consequences arising from the use of incentives.
For the original review (published 2012) we searched the Cochrane Tobacco Addiction Group Specialized Register, with additional searches of MEDLINE, Embase, CINAHL, CSA databases and PsycINFO for terms relating to incentives, in combination with terms for smoking and tobacco use, and children and adolescents. The most recent searches were of the Cochrane Tobacco Addiction Group Specialized Register, and were carried out in December 2016.
We considered randomized controlled trials (RCTs) allocating children and adolescents (aged 5 to 18 years) as individuals, groups or communities to intervention or control conditions, where the intervention included an incentive aimed at preventing smoking uptake. We also considered controlled trials (CTs) with baseline measures and post-intervention outcomes.
Two review authors extracted and independently assessed the data. The primary outcome was the smoking status of children or adolescents at follow-up who reported no smoking at baseline. We required a minimum follow-up of six months from baseline and assessed each included study for risks of bias. We used the most rigorous definition of abstinence in each trial; we did not require biochemical validation of self-reported tobacco use for study inclusion. Where possible we combined eligible studies to calculate pooled estimates at the longest follow-up, using the Mantel-Haenszel fixed-effect method, grouping studies by study design.
We identified three eligible RCTs and five CTs, including participants aged 11 to 14 years, who were non-smokers at baseline. Of the eight trials identified, six had analyzable data relevant for this review, which contributed to meta-analyses (7275 participants in total: 4003 intervention; 3272 control; 2484 participants after adjusting for clustering). All except one of the studies tested the 'Smokefree Class Competition' (SFC), which has been widely implemented throughout Europe. In this competition, classes with youth generally between the ages of 11 and 14 years commit to being smoke-free for a six-month period, and report their smoking status regularly. If 90% or more of the class are non-smokers at the end of the six months, the class goes into a competition to win prizes. The one study that was not a trial of the SFC was a controlled trial in which schools in two communities were assigned to the intervention, with schools in a third community acting as controls. Students in the intervention community with lower smoking rates at the end of the project (one school year) received rewards.Most studies resulted in statistically non-significant results. Only one study of the SFC reported a significant effect of the competition on the prevention of smoking at the longest follow-up. However, this study was at risk of multiple biases, and when we calculated the adjusted risk ratio (RR) we no longer detected a statistically significant difference. The pooled RR for the more robust RCTs (3 studies, n = 3056 participants/1107 adjusted for clustering) suggests that there is no statistically significant effect of incentives, in the form of the SFC, to prevent smoking initiation among children and adolescents in the long term (RR 1.00, 95% confidence interval (CI) 0.84 to 1.19). Pooled results from the non-randomized trials also did not detect a significant effect of the SFC, and we were unable to extract data on our outcome of interest from the one trial that did not study the SFC. There is little robust evidence to suggest that unintended consequences (such as making false claims about their smoking status and bullying of smoking students) are consistently associated with such interventions, although this has not been the focus of much research. There was insufficient information to assess the dose-response relationship or to report costs of incentives for preventing smoking uptake.We judged the included RCTs to be at unclear risk of bias, and the non-RCTs to be at high risk of bias. Using GRADE, we rated the overall quality of the evidence for our primary outcome as 'low' (for RCTs) and 'very low' (for non-RCTs), because of imprecision (all studies had wide confidence intervals), and for the risks of bias identified. We further downgraded the non-RCT evidence, due to issues with the non-RCT study design, likely to introduce further bias.
AUTHORS' CONCLUSIONS: The very limited evidence currently available suggests that incentive programmes do not prevent smoking initiation among youth. However, there are relatively few published studies and these are of variable quality. In addition, trials included in the meta-analyses were all studies of the SFC, which distributed small to moderately-sized prizes to whole classes, usually through a lottery system. It is therefore possible that other incentive programmes could be more successful at preventing smoking uptake in young people.Future studies might investigate the efficacy of a wider range of incentives, including those given to individual participants to prevent smoking uptake, whilst considering both the effect of incentives on smoking initiation and the progression to smoking. It would be useful if incentives were evaluated in varying populations from different socioeconomic and ethnic backgrounds, and if intervention components were described in detail.
成人吸烟通常始于青少年时期。如果个体在此期间不开始吸烟，那么他们日后吸烟的可能性就很小。此外，一旦吸烟行为确立，戒烟就具有挑战性；随后戒烟的可能性与开始吸烟的年龄成反比。一种降低青少年吸烟率的新方法是使用激励措施。
评估激励措施对预防儿童和青少年（5至18岁）开始吸烟的效果。我们还打算在可能的情况下评估激励措施的剂量反应、激励计划的成本、激励措施与其他预防吸烟开始的干预措施联合使用时是否更有效，以及使用激励措施产生的任何意外后果。
对于最初的综述（2012年发表），我们检索了Cochrane烟草成瘾小组专业注册库，并对MEDLINE、Embase、CINAHL、CSA数据库和PsycINFO进行了额外检索，以查找与激励措施相关的术语，并结合吸烟和烟草使用以及儿童和青少年的术语。最近的检索是在2016年12月对Cochrane烟草成瘾小组专业注册库进行的。
我们考虑将儿童和青少年（5至18岁）作为个体、群体或社区分配到干预或对照条件下的随机对照试验（RCT），其中干预措施包括旨在预防吸烟的激励措施。我们还考虑了具有基线测量和干预后结果的对照试验（CT）。
两位综述作者提取并独立评估数据。主要结局是在基线时报告不吸烟的儿童或青少年在随访时的吸烟状况。我们要求从基线开始至少随访六个月，并评估每项纳入研究的偏倚风险。我们在每个试验中使用了最严格的戒烟定义；纳入研究时我们不要求对自我报告的烟草使用进行生化验证。在可能的情况下，我们合并符合条件的研究，使用Mantel-Haenszel固定效应方法在最长随访时计算合并估计值，并按研究设计对研究进行分组。
我们确定了三项符合条件的RCT和五项CT，包括11至14岁的参与者，他们在基线时不吸烟。在确定的八项试验中，六项有与本综述相关的可分析数据，这些数据用于荟萃分析（总共7275名参与者：4003名干预组；3272名对照组；调整聚类后有2484名参与者）。除一项研究外，所有研究都测试了在欧洲广泛实施的“无烟班级竞赛”（SFC）。在这个竞赛中，年龄一般在11至14岁之间的班级承诺在六个月内无烟，并定期报告他们的吸烟状况。如果在六个月结束时班级中90%或更多的学生不吸烟，该班级将参加竞赛以赢取奖品。唯一一项不是SFC试验的研究是一项对照试验，其中两个社区的学校被分配到干预组，第三个社区的学校作为对照组。在项目（一学年）结束时吸烟率较低的干预社区的学生获得奖励。大多数研究结果在统计学上无显著意义。只有一项关于SFC的研究报告了在最长随访时竞赛对预防吸烟有显著效果。然而，这项研究存在多种偏倚风险，当我们计算调整后的风险比（RR）时，我们不再检测到统计学上的显著差异。更可靠的RCT（3项研究，n = 3056名参与者/调整聚类后1107名）的合并RR表明，以SFC形式的激励措施对长期预防儿童和青少年开始吸烟没有统计学上的显著效果（RR 1.00，95%置信区间（CI）0.84至1.19）。非随机试验的合并结果也未检测到SFC有显著效果，并且我们无法从唯一一项未研究SFC的试验中提取关于我们感兴趣结局的数据。几乎没有有力证据表明意外后果（如对其吸烟状况进行虚假宣称以及欺凌吸烟学生）与此类干预措施始终相关，尽管这尚未成为许多研究的重点。没有足够的信息来评估剂量反应关系或报告预防吸烟开始的激励措施成本。我们判断纳入的RCT存在偏倚风险不明确，非RCT存在高偏倚风险。使用GRADE，我们将主要结局的证据总体质量评为“低”（对于RCT）和“极低”（对于非RCT），原因是不精确（所有研究的置信区间都很宽）以及已识别的偏倚风险。由于非RCT研究设计的问题可能会引入进一步的偏倚，我们进一步降低了非RCT证据的等级。
目前非常有限的证据表明激励计划不能预防青少年开始吸烟。然而，可以获得的已发表研究相对较少，且这些研究质量参差不齐。此外，荟萃分析中纳入的试验都是关于SFC的研究，该竞赛通常通过抽签系统向整个班级发放小到中等规模的奖品。因此，其他激励计划可能在预防年轻人吸烟方面更成功。未来的研究可能会调查更广泛的激励措施的效果，包括给予个体参与者以预防吸烟的激励措施，同时考虑激励措施对开始吸烟和吸烟进展的影响。如果在来自不同社会经济和种族背景的不同人群中评估激励措施，并详细描述干预组成部分，将是很有用的。
