Smoking Prevention Trial Research Articles

Evaluation of a medical student-delivered smoking prevention program utilizing a face-aging mobile app for secondary schools in Germany: The Education Against Tobacco cluster-randomized controlled trial

BackgroundTo reduce smoking uptake in adolescents, the medical students' network Education Against Tobacco (EAT) has developed a school-based intervention involving a face-aging mobile app (Smokerface). MethodsA two-arm cluster-randomized controlled trial was conducted, evaluating the 2016 EAT intervention, which employed the mobile app Smokerface and which was delivered by medical students. Schools were randomized to intervention or control group. Surveys were conducted at baseline (pre-intervention) and at 9, 16, and 24 months post-intervention via paper & pencil questionnaires. The primary outcome was the difference in within-group changes in smoking prevalence between intervention and control group at 24 months. ResultsOverall, 144 German secondary schools comprising 11,286 pupils participated in the baseline survey, of which 100 schools participated in the baseline and at least one of the follow-up surveys, yielding 7437 pupils in the analysis sample. After 24 months, smoking prevalence was numerically lower in the intervention group compared to control group (12.9 % vs. 14.3 %); however, between-group differences in change in smoking prevalence between baseline and 24-months follow-up (OR=0.83, 95 %-CI: 0.64–1.09) were not statistically significant (p = 0.176). Intention to start smoking among baseline non-smokers declined non-significantly in the intervention group (p = 0.064), and remained essentially unchanged in the control group, but between-group differences in changes at the 24-months follow-up (OR=0.88, 0.64–1.21) were not statistically significant (p = 0.417). ConclusionWhile a trend towards beneficial effects of the intervention regarding smoking prevalence as well as intention to start smoking among baseline non-smokers was observed, our smoking prevention trial demonstrated no significant effect of the intervention.

Predicting longitudinal changes in patterns of tobacco and nicotine product use among adolescents: A Latent Transition Analysis based on the X:IT study

IntroductionUnderstanding factors influencing the transition from non-use to tobacco and nicotine product initiation among adolescents is crucial for designing and implementing effective preventive strategies. This study explores transition patterns among 13–15-year-old adolescents in lower secondary school, focusing on the transition from non-use to tobacco and nicotine product initiation and the influence of individual, social, risk behavioral, and mental health factors on this transition. MethodsBased on data from a Danish smoking prevention trial between 2017 and 2019, this study employed questionnaire surveys at three time points: baseline (start of seventh grade, n = 1,990, response rate = 86.3%), eight-month follow-up (end of seventh grade, n = 1,666, response rate = 74,8%), and 20-month follow-up (end of eighth grade, n = 1,149, response rate = 70,6%). Tobacco and nicotine use indicators included current and lifetime use of cigarettes and lifetime use of e-cigarettes, smokeless tobacco, and hookah. A latent transition analysis was applied to identify longitudinal transition patterns across waves and to explore predictors of these patterns. ResultsThree user classes emerged across all waves: none-use, lifetime e-cigarette and cigarette use, and poly-tobacco use. While the most prevalent class was the non-user class (71%–86%), the proportion of the lifetime e-cigarette and cigarette class increased over time (from 12% to 17%). Similarly, the poly-tobacco user class increased from 2% to 12%. The probability of transitioning from non-use to lifetime e-cigarette and cigarette use increased from 0.5% at baseline to 12% by the second follow-up, while the probability of transitioning from lifetime e-cigarette and cigarette use remained stable over time (12%–15%). Across all waves, elevated risk behavior predicted this transition. For instance, binge-drinking (OR = 3.76, 95% CI: 1.51–9.34), susceptibility to smoking (OR = 7.63, 95% CI: 3.68–16.83), and truancy (OR = 7.00, 95% CI: 1.98–24.59) influenced the transition from non-use at baseline to lifetime e-cigarette and cigarette use at first follow-up. Additionally, boys, adolescents with low socioeconomic status, low life satisfaction, and those with smoking friends or parents were more likely to transition from non-use to lifetime e-cigarette and cigarette use. ConclusionThis study demonstrates that sociodemographic, social risk, behavioral, and mental health factors impact the transition from non-use to lifetime e-cigarette and cigarette use. The findings provide valuable insights for developing targeted preventive strategies focusing on these influencing factors.

Implementation fidelity and adolescent smoking: The X:IT study—A school randomized smoking prevention trial

BackgroundAssessing the actual implementation of multi-component interventions can provide important knowledge for future interventions. Intervention components may be implemented differently, knowledge about this can provide an understanding of which components are essential and therefore must be included. The aim of this study was to examine the implementation of one, two, or all three main intervention components at the individual level and to assess the association to current smoking among 13 year-olds in the X:IT study. MethodsData stems from a cluster-randomized controlled trial in 94 Danish elementary schools (51 intervention; 43 control schools). Implementation was measured by aspects of adherence, dose, quality of delivery, and participant responsiveness based on questionnaire data from 4161 pupils at baseline (mean-age: 12.5 years) and 3764 pupils at first follow-up eight months later. Coordinator responses from 49 intervention schools were also included. Associations between individual level implementation of the three main components and pupil smoking were examined through a 3-level logistic regression model. ResultsAlthough implementation fidelity for the three main intervention components was good, only one third (38.8%) of pupils in intervention schools were exposed to full implementation of the intervention. Among these pupils odds ratio for smoking was 0.25 (95% CI: 0.15 – 0.42). ConclusionsSchool-based programs can be very effective if carefully implemented. Future school-based smoking preventive initiatives should include multiple components, and seek to enhance implementation quality of all components.

High impact of implementation on school-based smoking prevention: the X:IT study-a cluster-randomized smoking prevention trial.

BackgroundImplementation fidelity describes how well an intervention is implemented in the real-world setting. Assessing implementation fidelity is essential in the understanding of intervention results. In most studies, implementation fidelity is measured insufficiently, though, not taking into account the complexity of the concept nor the intervention.The objective of the present study was to develop an overall quantitative measure of implementation fidelity, to examine the degree of implementation fidelity and the association of implementation and effect of a randomized school-based smoking prevention trial—the X:IT study.MethodsA cluster-randomized trial testing is a multi-component intervention to prevent smoking among adolescents in 94 Danish elementary schools (51 intervention, 43 control schools). Participants were grade 7 pupils (mean age 12.5 years). Data was collected by electronic questionnaires among pupils at baseline (n = 4161), the first follow-up (n = 3764), and the second follow-up (n = 3269) and among school coordinators at intervention schools at the first and second follow-up (50 and 39 coordinators).Intervention: The intervention included three components: (1) smoke-free school grounds, (2) smoke-free curriculum, and (3) parental involvement, contracts, and dialogues. Implementation fidelity was assessed by four domains: adherence, dose, quality of delivery, and participant responsiveness. These were combined into an overall school-wise implementation index. The association of implementation and smoking was examined by logistic regression analyses.ResultsOne fourth of the schools was characterized as high implementers of the program (all three components) at both first (12 schools, 24.0 %) and second follow-up (11 schools, 28.2 %). Implementation fidelity was strongly associated with smoking at the first and second follow-up, e.g., the odds for smoking at schools with high implementation both years were OR = 0.44 (95 % CI 0.32 to 0.68).ConclusionsUsing an overall measure based on several aspects of implementation fidelity, we showed a negative graded association between implementation and smoking. This study suggests that higher degrees of implementation will improve the effect of the X:IT intervention. Studying the association between implementation and effect is extremely important; only by doing so, we can distinguish the quality of the intervention from the success of the implementation.Trial registrationCurrent Controlled Trials ISRCTN77415416

Berlin evaluates school tobacco prevention - BEST prevention: study design and methodology.

BackgroundThe hazardous health effects of smoking are established, but there remains a need to evaluate existing smoking prevention strategies and to increase their effectiveness in adolescents. Strategies focusing on parental attitudes and rule setting have been identified as a potentially effective approach. The present manuscript describes objectives, study design and methodology of the BEST Prevention study.Methods/designBEST Prevention is a three-armed cluster randomized-controlled trial among 7th grade (11–16 years) students in Berlin, Germany. Schools were enrolled between 2010 and 2011 and allocated using a centralized randomization list into 1) a student smoking prevention intervention (visit to an established interactive circuit), 2) the same intervention plus a parent intervention, and 3) a control group (visit to an established exercise and nutrition interactive circuit). Students were assessed at baseline, 12 and 24 months via self-report, as well as via carbon monoxide and cotinine in saliva at the 24 month follow-up. Statistical analyses uses multi-level regression models with cluster effects (school and class within school) based on the intention to treat population. Here we report descriptive baseline characteristics of recruited schools, and schools classes. Two schools from the control group dropped out after allocation. Hence, 47 secondary schools from all 12 districts of the city, including 161 school classes and 3023 students are participating in the study. Of those, 2801 students completed the baseline assessment.DiscussionThe present manuscript provides details on the study design and methodology of a large school-based smoking prevention trial in a metropolitan area in Germany. Findings from this study will yield important insight into the long-term effectiveness of specific smoking prevention strategies, also in disadvantaged population groups.Trial registrationNCT01306552 (January 2011).

Poster #M117 EVIDENCE THAT CHILDHOOD URBAN ENVIRONMENT IS ASSOCIATED WITH BLUNTED STRESS REACTIVITY ACROSS GROUPS OF PSYCHOTIC PATIENTS, RELATIVES AND CONTROLS

Background: This study reports the prevalence of adolescent smoking in the urban and rural areas of Wuhan, China, the capital of Hubei Province, on the Yangtze River in central China.Methods: Smoking behavior was examined by age, gender, and urbanicity as part of the Wuhan Smoking Prevention Trial. Subjects included 6994 seventh- to ninth-grade students attending 22 randomly selected schools in urban and rural districts. Outcome measures included lifetime smoking, past-30-day smoking, established smoking (>100 cigarettes in lifetime), and susceptibility to smoking (absence of a firm commitment not to smoke).Results: Lifetime smoking prevalence was 47% among boys and 18% among girls. Past-30-day smoking prevalence was 16% among boys and 4% among girls. Established smoking prevalence was 2% among boys and 0% among girls. The prevalence of susceptibility to smoking was 31% among boys and 10% among girls. Smoking increased significantly with age (p<.0005). Susceptibility was more prevalent in rural areas than in urban areas (p<.05), but there were no urban-rural differences in lifetime, past 30-day smoking, or established smoking. Trend analyses revealed that smoking increased with age more rapidly among boys than among girls (p<.05). Smoking was more prevalent among rural boys than among urban boys, but it was more prevalent among urban girls than among rural girls (p<.05).Conclusions: Adolescent smoking is a significant public health problem in China. Boys are at particularly high risk, as are girls living in urban areas. Effective smoking prevention programs for adolescents, as well as restrictions on tobacco industry marketing and youth access to tobacco, are needed to prevent tobacco-related morbidity and mortality in China.

Reaching Jewish ultra-orthodox adolescents: results from a targeted smoking prevention trial

Ultra-orthodox, Jewish adolescent boys are considered to have relatively high smoking rates, but are generally not targeted by Israel's smoking prevention programs. The objective of this trial was to test the effectiveness of a religion-based tobacco control intervention in reducing smoking prevalence among these youth. The study population participants were 340 boys from 63 religious boys' schools in Jerusalem. The intervention consisted of a mailing that included a pamphlet describing the health effects of and rabbinical prohibitions on smoking. A cluster randomized trial was conducted between March and May, 2005. The primary endpoint was current smoking status. Secondary endpoints were future intent to smoke and attitudes towards smoking. Generalized estimating equations and mixed models of analysis of variance were used to perform the analyses. The intervention did not significantly affect current smoking, intent to smoke or attitudes towards smoking. Prevalence of smoking and future intent to smoke were higher in schools without enforced smoking regulations [odds ratio (OR) 2.74, p=0.026, OR 3.38, p=0.018]. Increased smoking prevalence was associated with a high prevalence of smoking among friends (p=0.031) and not finding smoking repulsive (p=0.024). This study adds to the public health literature linking smoke-free schools and peer influences to adolescent smoking. Pamphlets containing rabbinic prohibitions on smoking initiation did not affect smoking behavior or intent to smoke.

Association of the Calcyon Neuron-Specific Vesicular Protein Gene (CALY) With Adolescent Smoking Initiation in China and California

Although previous investigations have indicated a role for genetic factors in smoking initiation, the underlying genetic mechanisms are still unknown. In 2,339 adolescents from a Chinese Han population in the Wuhan Smoking Prevention Trial (Wuhan, China, 1998-1999), the authors explored the association of 57 genes in the dopamine pathway with smoking initiation. Using a conservative approach for declaring significance, positive findings were further examined in an independent sample of 603 Caucasian adolescents followed for up to 10 years as part of the Children's Health Study (Southern California, 1993-2009). The authors identified 1 single nucleotide polymorphism (rs2298122) in the calcyon neuron-specific vesicular protein gene (CALY) that was positively associated with smoking initiation in females (odds ratio = 2.21, 95% confidence interval: 1.49, 3.27; P = 8.4 × 10(-5)) in the Wuhan Smoking Prevention Trial cohort, and they replicated the association in females from the Children's Health Study cohort (hazard rate ratio = 2.05, 95% confidence interval: 1.27, 3.31; P = 0.003). These results suggest that the CALY gene may influence smoking initiation in adolescents, although the potential roles of underlying psychological characteristics that may be components of the smoking-initiation phenotype, such as impulsivity or novelty-seeking, remain to be explored.

Tobacco Use Harm Reduction, Elimination, and Escalation in a Large Military Cohort

We evaluated changing patterns of tobacco use following a period of forced tobacco abstinence in a US military cohort to determine rates of harm elimination (e.g., tobacco cessation), harm reduction (e.g., from smoking to smokeless tobacco use), and harm escalation (e.g., from smoking to dual use or from smokeless tobacco use to smoking or dual use). Participants were 5225 Air Force airmen assigned to the health education control condition in a smoking cessation and prevention trial. Tobacco use was assessed by self-report at baseline and 12 months. Among 114 baseline smokers initiating smokeless tobacco use after basic military training, most demonstrated harm escalation (87%), which was 5.4 times more likely to occur than was harm reduction (e.g., smoking to smokeless tobacco use). Harm reduction was predicted, in part, by higher family income and belief that switching from cigarettes to smokeless tobacco is beneficial to health. Harm escalation predictors included younger age, alcohol use, longer smoking history, and risk-taking. When considering a harm reduction strategy with smokeless tobacco, the tobacco control community should balance anticipated benefits of harm reduction with the risk of harm escalation and the potential for adversely affecting public health.

Evaluating depressive symptom interactions on adolescent smoking prevention program mediators: a mediated moderation analysis.

Smoking prevention interventions have been shown to be effective in reducing smoking prevalence in the United States. Further work is needed to address smoking in China, where over one third of the world's current smokers reside. China, with more than 60% of the male population being smokers, also presents a unique opportunity to test cognitive processes involved in depression, social influences, and smoking. Adolescents at-risk for developing depression may process social information differently from low-risk counterparts. The Wuhan Smoking Prevention Trial was a school-based longitudinal randomized controlled trial aimed at preventing initiation and escalation of adolescent smoking behaviors. Thousand three hundred and ninety-one male seventh-grade students were assessed with a 200-item paper-and-pencil baseline survey, and it was readministered 1 year later following program implementation. Friend prevalence estimates were significantly higher among 30-day smokers and among those at highest risk for depression symptoms. The program appeared to be successful in changing the perception of friend smoking prevalence only among adolescents with a comorbidity of high scores of depression symptoms and who have experimented previously with smoking. This Program x Comorbidity interaction on perceived friend smoking prevalence was significant in predicting 30-day smoking 1 year after program implementation. This study provides evidence that those adolescents with high levels of depressive symptoms may be more sensitive to social influences associated with smoking prevalence. Individual Disposition x Social Environmental Influences may be important when developing future effective prevention programming.

Comorbidity between depression and smoking moderates the effect of a smoking prevention program among boys in China

Smoking prevention programs based on social influences have reduced smoking prevalence among youth. However, these effects have not been replicated consistently. It is possible that individuals and populations with different dispositional and behavioral characteristics will experience different program effects. This study explored a possible moderation of program effect by comorbidity between depression and smoking (CoM). Data for this analysis were from 2,450 seventh-grade youth (51% boys) who participated in the Wuhan (China) Smoking Prevention Trial (WSPT). WSPT was a randomized, controlled, 14-session, middle-school-based smoking prevention trial. Baseline and 1-year follow-up surveys were administered. The moderation effect between the program and CoM was tested on 1-year change in recent smoking. The CoM indicator was defined dichotomously as monthly cigarette use and high in depression level (among the top 20% in the sample). At baseline, a total of 26 girls and 60 boys were identified to have CoM. Among boys (but not girls), CoM significantly moderated the program effect on recent smoking (p = .01). The program effect among boys with CoM was 4.17 (95% CI 1.47-11.76) times larger than those without CoM. Among boys with CoM, the odds ratio of recent smoking was 0.18 (95% CI 0.06-0.55) for program vs. control condition. Among those without CoM, the program did not reduce the odds of recent smoking significantly (OR = 0.74, 95% CI 0.37-1.48). The study demonstrated that smoking prevention program effects can vary with individual characteristics, in this case comorbidity between depression and smoking. These findings may help explain the inconsistency in program effects across studies and populations. The findings also may contribute to the design of future programs to address the needs of defined populations and individuals with specific characteristics.

Which psychosocial factors moderate or directly affect substance use among inner-city adolescents?

Past etiology of adolescent substance use research concentrated on the main effects of various risk factors. The purpose of this study was to also longitudinally predict interactions on poly-drug use intensity and future smoking among inner-city adolescents. A panel sample of baseline, 1-year and 2-year follow-ups ( N = 1459) from the control group of a longitudinal smoking prevention trial participated. We focused on the main effects, as well as, interaction effects between psychosocial protective factors and various risk factors, including perceived norms of friends, peers and adults to use drugs. Significant effects were identified for intensity of poly-drug use and future smoking. The analysis of the poly-drug use outcome indicated that refusal assertiveness undermined perceived friends' drug use and siblings' smoking, and that low risk-taking undermined perceived friends' drug use. There was a main effect for low psychological wellness. The significant interactions between perceived friends' drug use with refusal assertiveness and decision-making skills were observed for future smoking. Moreover, perceived peer smoking norms, siblings' smoking, and high risk-taking also showed significant main effects for increasing future smoking.

Physician Tobacco Advice to Preteens in a Smoking-Prevention Randomized Trial: Steering Clear

To examine preadolescent and parental recall of tobacco prevention messages by health care providers. As part of a smoking prevention trial, providers were cued to reinforce the study and advise intervention participants (N=4,026) not to use tobacco. All parents were surveyed at baseline; children were surveyed at 20 months; and a subsample (504 households) was surveyed at 6 and 12 months to assess discussion of tobacco use prevention and other health behavior topics by providers as well as susceptibility and experimentation with tobacco among children. During the 20-month follow-up, less than 25% of children recalled a provider discussing tobacco use prevention. Recall of exposure to tobacco prevention messages at school (68%), from parents (53%), and from mass media (71%) was higher. Physician tobacco counseling is occurring at lower rates in pre-adolescents than it is in adults. A chart reminder to providers was insufficient to create a meaningful effect.

A mixed-effects regression model for three-level ordinal response data

Three-level data occur frequently in behaviour and medical sciences. For example, in a multi-centre trial, subjects within a given site are randomly assigned to treatments and then studied over time. In this example, the repeated observations (level-1) are nested within subjects (level-2) who are nested within sites (level-3). Similarly, in twin studies, repeated measurements (level-1) are taken on each twin (level-2) within each twin pair (level-3). A three-level mixed-effects regression model is described here. Random effects at the second and third level are included in the model. Additionally, both proportional odds and non-proportional odds models are developed. The latter allows the effects of explanatory variables to vary across the cumulative logits of the model. A maximum marginal likelihood (MML) solution is described and Gauss-Hermite numerical quadrature is used to integrate over the distribution of random effects. The random effects are normally distributed in this instance. Features of this model are illustrated using data from a school-based smoking prevention trial and an Alzheimer's disease clinical trial.

Written Parental Consent and the Use of Incentives in a Youth Smoking Prevention Trial: A Case Study From Project SPLASH

More Institutional Review Boards (IRBs) are requiring written parental consent in school health intervention trials. Because this requirement presents a formidable challenge in conducting large-scale research, it is vital for investigators to share effective strategies learned from completed trials. Investigators for the recently completed Project SPLASH ( n = 3,716) smoking prevention trial, conducted in 20 Hawaii middle schools, were required to obtain active parental consent for three surveys across 2 years. This case study describes the consent procedures and incentives used in the trial, and their effectiveness. The overall parental response rate was 85.4%. The highest response rate (89.5%) came from the 7th grade baseline survey, where project staff distributed consent materials and provided class-based incentives. In addition, nearly all students (99.0%) with parental permission assented to participate in the three surveys. The experiences in this study lead to several recommendations for future research, including the importance of assuring adequate funds for recruitment and retention in research grants.

Methods for modelling change in cluster randomization trials.

Randomized trials are often designed to assess an intervention's ability to change patient knowledge, behaviour or health. The study outcome will then need to be measured at least twice for each subject--prior to random assignment and following implementation of the intervention. In this paper we consider methods for modelling change when data are obtained from cluster randomization trials where the unit of allocation is a family, school or community. Attention focuses on mixed effects linear regression extensions of (i) two-sample t-tests and (ii) analysis of covariance, in both cases accounting for dependencies among cluster members. Algebraic expressions for tests of the intervention effect are derived for the special case where there are a fixed number of subjects per cluster while simulation studies are used to compare the power of these procedures in the more realistic case where there is variability in cluster size. A key conclusion is that there can be considerable gains in power when allowing for different individual-level and cluster-level associations between the baseline and follow-up assessments. The discussion is illustrated using data from a school-based smoking prevention trial.

Sensations from initial exposure to nicotine predicting adolescent smoking in China: a potential measure of vulnerability to nicotine.

Sensations derived from initial exposure to nicotine are a potential indicator of an individual's vulnerability to nicotine. This study assessed whether sensations experienced during the first lifetime exposure to nicotine could predict current and established cigarette smoking. Data from 210 respondents who reported having ever tried cigarette smoking in Wuhan, China, were obtained for this study from 610 students in 10th grade at two schools. Subjects were participants in a multipurpose pilot survey for an adolescent smoking prevention trial. The survey was administered in a classroom setting using a paper-and-pencil questionnaire. Sensations reported were cigarette smell (59.2%), coughing (54.1%), dizziness (52.1%), nausea (42.5%), relaxation (19.1%), and pleasurable buzz/rush (9.0%). After controlling for confounders, multiple logistic regression analyses identified three sensations significantly associated with smoking: (a) Cigarette smell (OR for days smoked in the past 30 days=2.93, p<.05, OR for number of cigarettes smoked per day=2.69, p<.05, and OR for 100-cigarette smoking=5.40, p<.01), (b) pleasurable buzz/rush (OR for 100-cigarette smoking=11.09, p<.05), and (c) relaxation (OR for past 30-day smoking measures ranged from 3.69 to 4.48, p<.01, and OR for 100-cigarette smoking=4.12, p<.05). A dose-response relationship was observed between the sensations and cigarette smoking. Self-reported sensations from initial exposure to nicotine may be a useful indicator of an individual's vulnerability to nicotine. This information can be used for adolescent smoking prevention and cessation interventions.

Marginal Methods for Incomplete Longitudinal Data Arising in Clusters

Inverse probability–weighted generalized estimating equations are commonly used to deal with incomplete longitudinal data arising from a missing-at-random mechanism when the marginal means are of primary interest. In many cases, however, the repeated measurements themselves may arise in clusters, which leads to both a cross-sectional and a longitudinal correlation structure. In some applications, the degree of these types of correlation may become of scientific interest. Here we develop inverse probability–weighted second-order estimating equations for monotone missing-data patterns which, under specified assumptions, facilitate consistent estimation of the marginal mean parameters and association parameters. Here the missing-data model accommodates cross-sectional clustering in the missing-data indicators, and the probabilities are estimated under a multivariate Plackett model. For computational reasons, we also consider using the alternating logistic regression algorithm for estimation of the association parameters for the responses. We investigate the importance of modeling the cross-sectional clustering in the missing-data process by simulation. An extension to deal with intermittently missing data is provided, and an application to a longitudinal cluster-randomized smoking prevention trial is presented.

Short-Term Effects of a Randomized Computer-Based Out-of-School Smoking Prevention Trial Aimed at Elementary Schoolchildren

Background. Smoking prevention programs usually run during school hours. In our study, an out-of-school program was developed consisting of a computer-tailored intervention aimed at the age group before school transition (11- to 12-year-old elementary schoolchildren). The aim of this study is to evaluate the additional effect of out-of-school smoking prevention.Methods. One hundred fifty-six participating schools were randomly allocated to one of four research conditions: (a) the in-school condition, an existing seven-lesson program; (b) the out-of-school condition, three computer-tailored letters sent to the students' homes; (c) the in-school and out-of-school condition, a combined approach; (d) the control condition. Pretest and 6 months follow-up data on smoking initiation and continuation, and data on psychosocial variables were collected from 3,349 students.Results. Control and out-of-school conditions differed regarding posttest smoking initiation (18.1 and 10.4%) and regarding posttest smoking continuation (23.5 and 13.1%). Multilevel logistic regression analyses showed positive effects regarding the out-of-school program. Significant effects were not found regarding the in-school program, nor did the combined approach show stronger effects than the single-method approaches.Conclusions. The findings of this study suggest that smoking prevention trials for elementary schoolchildren can be effective when using out-of-school computer-tailored interventions.

Peer Influences and Access to Cigarettes as Correlates of Adolescent Smoking: A Cross-Cultural Comparison of Wuhan, China, and California

Background. Few studies have assessed the effects of access to cigarettes and peer influences on adolescent smoking in non-Western countries. Using samples characterized by two distinct cultural, social, and economic systems, this study evaluated the associations of friends' smoking and perceived access to cigarettes with adolescent smoking behavior in California and Wuhan, China.Methods. Survey data were obtained from 5870 eighth-grade students in the Independent Evaluation of the California Tobacco Control Program and 6992 seventh- to ninth-grade students in the Wuhan Smoking Prevention Trial. Odds ratios for lifetime and 30-day smoking, according to friends' smoking and perceived access to cigarettes, were calculated for boys and girls in both samples and compared.Results. California students were more likely than Wuhan students to have friends who smoked and to perceive easy access to cigarettes. The smoking prevalence was lower in Wuhan than in California, mainly due to the low smoking prevalence among Wuhan girls. Friends' smoking was strongly associated with smoking in both samples, and the strength of this association did not differ between the two cultures. Access to cigarettes was associated with a higher risk of lifetime smoking in both cultures and a higher risk of past 30-day smoking in California only.Conclusions. Despite divergent tobacco control policy enforcement, social structures, and cultural contexts, similarities exist between Wuhan and California. The findings suggest support for adapting a social-influences-based smoking prevention program developed in the United States to the culturally specific needs of youth in Wuhan, China.