Beyond quitting: predictors of teen smoking cessation, reduction and acceleration following a school-based intervention

Association between anti-smoking campaign types and smoking cessation attempts

Objective

This study explored the association between anti-smoking campaign types and smoking cessation attempts.

Methods

This study included 4,594 individuals (3,292 male and 1,302 female) from the Korea Youth Risk Behavior Web-based Survey (KYRBWS) in 2018 and 2020. The methods of anti-smoking promotion were divided into online, offline, online and offline, and none. Attempts to quit smoking were classified as yes or no. Multiple logistic regression was performed to examine the association between antismoking campaign type and smoking cessation attempts.

Results

Those who saw anti-smoking advertisements both online and offline were found to have tried to quit smoking more than those who did not. (Online & offline: male, odds ratio [OR] 1.36; 95% confidence interval [95% CI], 1.08-1.71; female, OR, 1.75; 95% CI 1.21-2.54) In a subgroup analysis of the independent variables into which smoking cessation advertisements were subdivided, males were found to have the highest OR for smoking cessation attempts when they encountered advertisements in newspapers. (Newspaper: male, OR, 2.25; 95% CI, 1.00-5.02) Females had the highest OR for smoking cessation attempts when accessed via the Internet. (Internet: female, OR, 1.93; 95% CI, 1.07-3.50).

Conclusion

This study showed that there is a correlation between smoking cessation advertisements and adolescents' smoking cessation attempts. The possibility of smoking cessation attempts is high when encountering smoking cessation advertisements both online and offline. Although offline smoking cessation advertisements have a great effect on adolescents' smoking cessation attempts, it can be confirmed that the frequency of exposure for offline advertisements is less than that for online advertisements.

Knowledge and practice of harm-reduction behaviours for alcohol and other illicit substance use in adolescents with type 1 diabetes

Objective

To survey adolescents with type 1 diabetes mellitus (T1DM) about their knowledge and application of harm-reduction recommendations when they engage in alcohol and other illicit substance use.

Methods

Cross-sectional survey and chart review of adolescents with T1DM aged 13 to 18 years.

Results

One hundred and ninety patients were approached and 164 were included in the analysis. Mean age was 15.6 years (standard deviation [SD]=1.5). Fifty-one per cent were male. Of those who reported consuming alcohol, 95% knew that they should have a friend or parent check their blood glucose in the middle of the night after drinking but only 62% reported actually doing this in practice. Similarly, 98% reported knowing that they should wear a medic alert identification but only 79% reported actually doing this. Of those who reported consuming cannabis, 14% reported forgetting to check blood glucose and 14% reported forgetting insulin when using cannabis. From the chart review, a significantly lower proportion of adolescents reported substance use during their clinic visits (alcohol 26%, tobacco 19%, illicit substance 25%) compared to the self report in the survey (alcohol 55%, tobacco 30%, illicit substance 32%).

Conclusions

Adolescents' knowledge of harm-reduction practices for the use of alcohol and other illicit substances is not always put to practice. Motivating adolescents to use their knowledge in practice is an important area to improve in diabetes self-management. Those who reported engaging in substance use in the survey had not always reported use during interactions with health care providers. This emphasizes the need for unbiased, universal education of all adolescents in the clinic.

School-level disadvantage and failed cessation treatment among adolescent smokers

INTRODUCTION

While understanding factors that lead to successful adolescent smoking cessation outcomes is necessary, it is also prudent to determine factors and conditions that contribute to failure to quit smoking. The present study posits that adolescents' proximal environments, such as schools, may influence cessation treatment outcomes.

METHODS

Using aggregated and geographically-referenced data from multi-year school-based cessation trials with 14-19 year olds seeking cessation in 5 States of the USA, the present study developed and applied a tobacco-specific socio-spatial model inclusive of Hierarchical Linear Modeling. Specifically, this novel approach spatially joined individual data files (n=8855) with measures of school (n=807) and county socio-economic factors. Once linked multi-level analyses explored the extent to which cessation treatment failure was explained by the interplay of individual, school and county-level factors. Treatment was deemed as failing to meet its primary goals if participants continued to smoke cigarettes, measured 3-months post baseline.

RESULTS

Ten per cent of the variation in cessation treatment failure was attributable to school-level variables. Adolescent smokers were more likely to experience failure to quit in: a) school districts with large percentages of the population having less than high-school education, and b) schools with a higher ratio of students to teachers. The strength of the relationship between cessation self-efficacy and treatment success was further weakened among adolescents attending schools with higher percentages of students eligible for free or reduced lunch programs.

CONCLUSIONS

Findings implicate school-level socio-economic disadvantage as a significant factor inhibiting cessation, regardless of adolescent self-efficacy to quit smoking. Understanding the interplay of proximal school environments and individual-level factors may provide insights to educators, policy makers and practitioners into the complexities that inhibit or strengthen an adolescent's smoking cessation treatment experience.

Impact of Age at Smoking Initiation on Smoking-Related Morbidity and All-Cause Mortality

INTRODUCTION

Using a nationally representative sample of U.S. adults, the aims of this study were to examine the impact of early smoking initiation on the development of self-reported smoking-related morbidity and all-cause mortality.

METHODS

National Health Interview Survey data from 1997 through 2005 were linked to the National Death Index with follow-up to December 31, 2011. Two primary dependent variables were smoking-related morbidity and all-cause mortality; the primary independent variable was age of smoking initiation. The analyses included U.S. population of current and former smokers aged ≥30 years (N=90,278; population estimate, 73.4 million). The analysis relied on fitting logistic regression and Cox proportional hazards models.

RESULTS

Among the U.S. population of smokers, 7.3% started smoking before age 13 years, 11.0% at ages 13-14 years, 24.2% at ages 15-16 years, 24.5% at ages 17-18 years, 14.5% at ages 19-20 years, and 18.5% at ages ≥21 years. Early smoking initiation before age 13 years was associated with increased risks for cardiovascular/metabolic (OR=1.67) and pulmonary (OR=1.79) diseases as well as smoking-related cancers (OR=2.1) among current smokers; the risks among former smokers were cardiovascular/metabolic (OR=1.38); pulmonary (OR=1.89); and cancers (OR=1.44). Elevated mortality was also related to early smoking initiation among both current (hazard ratio, 1.18) and former smokers (hazard ratio, 1.19).

CONCLUSIONS

Early smoking initiation increases risks of experiencing smoking-related morbidities and all-cause mortality. These risks are independent of demographic characteristics, SES, health behaviors, and subsequent smoking intensity. Comprehensive tobacco control programs should be implemented to prevent smoking initiation and promote cessation among youth.

Development and validation of a smoking expectancies measure for adolescents seeking to quit smoking

BACKGROUND

A more comprehensive understanding of factors that affect smoking cessation outcomes among adolescents may help enhance treatment interventions. One promising but underexplored factor that may influence cessation success is teens' specific expectancies or beliefs about smoking outcomes. The present study evaluated the validity and reliability of a new measure of expectancies and its association with cessation outcomes among 762 adolescent smokers participating in studies of the American Lung Association's Not On Tobacco cessation program.

METHODS

Self-report questionnaires were collected prior to and following participation in a smoking cessation program. Self-reported cigarette use was verified with expired-air carbon monoxide. A multistep exploratory and confirmatory factor analysis and reliability and validity analyses were performed.

RESULTS

Four theoretically related yet empirically independent factors were identified by the Smoking Expectancies Questionnaire (SEQ): (1) Positive Reinforcement, (2) Negative Reinforcement-Emotional Regulation, (3) Negative Reinforcement-Addiction and Withdrawal, and (4) Negative Outcomes/Risk. These factors could be subsumed by a single SEQ factor that reflected an overall concept of smoking expectancies relevant for adolescent smoking cessation. An overall SEQ Function score reflecting the balance between positive and negative expectancies predicted both preintervention cigarettes per day and cessation outcomes.

CONCLUSIONS

A single, overall SEQ Function score may prove useful for understanding the associations among individual, social, and contextual factors in predicting treatment outcomes. Additionally, study findings may assist with modifying smoking expectancies among cessation program participants, thereby enhancing treatment outcomes with diverse youth smoking populations.

Predictors of the Nicotine Dependence Behavior Time to the First Cigarette in a Multiracial Cohort

BACKGROUND

The time to first cigarette of the day (TTFC) is a strong indicator of nicotine dependence behaviors such as nicotine uptake and quit success in young and older smokers. There are substantial differences in levels of nicotine dependence by race and ethnic group.

METHODS

Data from Wave III of the multiracial National Longitudinal Study of Adolescent Health were analyzed for young smokers between the ages of 21 and 28 (N = 1,425). Time to first cigarette data was compared between Hispanic, White, Black, Native American, and Asian smokers.

RESULTS

Black smokers were significantly more likely to smoke within 5min of waking than White, Hispanic, and Asian smokers. Lower personal income predicted smoking within 5min of waking for both White and Black smokers. For White smokers, increased number of cigarettes per day and increased years of smoking also predicted smoking within 5min of waking. The number of days smoked or number of cigarettes per day did not predict smoking within 5min of waking among smokers.

CONCLUSIONS

The higher prevalence of early TTFC among Blacks indicates increased nicotine and carcinogen exposure, and may help explain the increased lung cancer rates and failed cessation attempts among Black smokers. TTFC may be an important screening item, independent of cigarettes per day, for clinicians and interventions to identify those at highest risk for cessation failure and disease risk.

Tobacco and alcohol use in the context of adolescent pregnancy and postpartum: a scoping review of the literature

Adolescent girls are more likely than women of other ages to smoke tobacco or drink alcohol during pregnancy. The health impacts of smoking and drinking for girls and the interconnections between alcohol and tobacco use with adolescent pregnancy underscore the urgent need for integrated approaches to prevent and reduce alcohol and tobacco use among pregnant girls/young women. This article reports on the results of a scoping review of the literature focused on adolescents' use of tobacco and alcohol during pregnancy and postpartum. A search of CINAHL, Medline, Social Science Index and Web of Science identified 40 articles published in the two decades between 1990 and 2012 that met our inclusion criteria related to this age group, pregnancy/motherhood status, and use of both alcohol and tobacco. The review points to compelling gaps in our knowledge and our responsiveness to adolescents aged 19 and under who use alcohol and tobacco during pregnancy and the postpartum period. Research has been primarily descriptive, with separate, parallel streams of investigation to identify trends and predictors of alcohol and tobacco use, prior to, during and following pregnancy. There is a marked lack of effective interventions described in the literature that are designed to prevent or reduce alcohol and tobacco use during pregnancy among adolescent girls; and there are few examples of gender-informed prevention or treatment programmes for this population. Research is needed on interventions that attend to the context of adolescent girls' substance use as well as their preferences and developmental needs for support that encourage sustained behaviour change throughout pregnancy and the postpartum period and that effectively address the influence of partners and friends on use.

Predictors of adolescent smoking cessation and smoking reduction

OBJECTIVE

To investigate the processes of change, demographic, health- and smoking-related predictors of both smoking cessation and smoking reduction in adolescents.

METHODS

Data were drawn from a sample of 755 adolescent smokers who participated in a study testing the efficacy of a text messaging-based intervention for smoking cessation. Demographic, health- and smoking-related variables were assessed at baseline. Five processes of smoking cessation, derived from the Transtheoretical Model and the Social Cognitive Theory, as well as outcome measures were assessed at 6-month follow up. Univariate and multivariate regression analyses were conducted to identify baseline and process variables to predict smoking abstinence and smoking reduction.

RESULTS

Male gender (OR=0.43, p<.01), lower alcohol consumption (OR=0.90, p=.05) and a lower number of cigarettes smoked per day at baseline (OR=0.87, p<.01) predicted smoking abstinence. Baseline physical activity predicted smoking reduction (OR=1.04, p=.03). None of the examined process variables significantly predicted smoking abstinence. The process variable "counter-conditioning" predicted smoking reduction (OR=1.46, p=.03).

CONCLUSIONS

Baseline predictors of smoking cessation differ from predictors of smoking reduction. Dynamic or modifiable variables play an important role in predicting adolescent smoking cessation.

PRACTICE IMPLICATIONS

Counter-conditioning might be an important element in adolescent smoking cessation interventions.

Time to first cigarette predicts 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in adolescent regular and intermittent smokers, National Health and Nutrition and Examination Survey (NHANES) 2007-10

BACKGROUND AND AIMS

The time to first cigarette (TTFC) of the day is an indicator of nicotine intake in adults and adolescents. However, the relation between TTFC and biological markers of nicotine addiction and health risk in youths has not been well described. The current study examined whether an earlier TTFC predicts higher levels of a tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridal)-1 (NNAL), in regular and intermittent adolescent smokers and if this relation is mediated by nicotine intake (measured by cotinine) or cigarettes per day (CPD).

DESIGN

A cross-sectional analysis of a nationally representative subsample of adolescents.

SETTING

A general community sample from the 2007-08 and 2009-10 National Health and Nutrition and Examination Survey.

PARTICIPANTS

A total of 215 adolescents in the United States between the ages of 12 and 19 years who reported smoking at least once in the 5 days prior to data collection.

MEASUREMENTS

The primary outcome measure was urinary levels of NNAL.

FINDINGS

In both regular and intermittent smokers, earlier TTFC was associated dose-dependently with higher levels of NNAL (P < 0.03 in both cases). TTFC had an indirect effect on NNAL, mediated by nicotine intake (cotinine) in both regular [β = -0.08, standard error (SE) = 0.03, 95% confidence interval (CI) = -0.15, -0.03] and intermittent (β = -0.02, SE = 0.01, 95% CI = -0.05, -0.002) smokers. CPD was not found to be an important mediator of the relation between TTFC and NNAL.

CONCLUSIONS

Time between waking and the first cigarette of the day is correlated in daily and non-daily adolescent smokers with overall nicotine and therefore carcinogen intake.

Factors associated with smoking among adolescent males prior to incarceration and after release from jail: a longitudinal study

Background

The prevalence of cigarette smoking among incarcerated adult men and women is three-four times higher than in the general population, ranging from 70-80%. However, little is known about factors associated with smoking among incarcerated adolescents, especially upon their re-entry into communities after release from jail. The current study explores factors associated with smoking among adolescent males prior to incarceration and one year after their release from jail.

Methods

We conducted a secondary data analysis of the Returning Educated African-American and Latino Men to Enriched Neighborhoods (REAL MEN) study, which was designed to reduce HIV risk, substance use, and recidivism among 16–18 year old males leaving jail. We examined differences between smokers and non-smokers at the time of their incarceration (N = 552) and one year after their release from jail (N = 397) using t-tests and chi-square tests. Using logistic and linear regression we examined factors associated with current smoking status, frequency of smoking, and quantity of cigarettes smoked per day both prior to the young men’s incarceration and one year after their release from jail.

Results

Prior to incarceration, 62% of the young men reported smoking, and one-year after jail release, 69% reported smoking. Prior to incarceration, foster care history, not living with parents, not attending school, drug sales, number of sex partners, gang involvement, current drug charges, and number of prior arrests were positively associated with smoking indicators prior to incarceration. Having violent charges was inversely associated with smoking indicators prior to incarceration. One-year after release from jail, foster care history and number of prior arrests before the index incarceration were associated with smoking indicators.

Conclusions

Several problem behaviors may be associated with adolescent males’ smoking behaviors prior to incarceration. However, the young men’s histories of difficult life circumstances and engagement in illegal activity may have long-term consequences on smoking for these young men during their transition between jail and community. Findings suggest a need for comprehensive risk reduction interventions in settings in which disadvantaged young men are institutionalized, starting in childhood.

Understanding physical activity outcomes as a function of teen smoking cessation

OBJECTIVE

Recent evidence suggests physical activity may be protective against smoking initiation and increased smoking among youth. The present study explored the effects of a teen smoking cessation intervention supplemented with a physical activity module on participants' physical activity outcomes. A secondary aim examined the relationship between participants' physical activity outcomes and postprogram smoking intensity.

DESIGN

The study reports primary data from a 3-arm randomized group trial consistent with CONSORT guidelines (Registry # NCT01242657).

SETTING

Public high schools (N = 19) in West Virginia.

PARTICIPANTS

Teens aged 14-19 years (N = 233) who reported current smoking, ≥1 cigarette in the past 30 days.

INTERVENTION

High schools were randomly selected, then randomly assigned to Brief Intervention (standard of care), Not-On-Tobacco (N-O-T, teen cessation program), or N-O-T plus a physical activity module (N-O-T+FIT).

OUTCOME MEASURES

Standardized instruments at baseline and end of treatment/3-months postbaseline measured physical activity outcomes. The study assessed smoking intensity using cigarettes smoked per day. We conducted ANCOVA controlling for school-level variance to measure physical activity changes. Multiple linear and logistic regression analyses explored favorable change influence of physical activity on smoking cessation outcomes, controlling for potential clustering.

RESULTS

Teens who increased the number of days on which they received at least 20 minutes of exercise were significantly more likely to reduce their daily cigarette use, with those in the N-O-T+FIT condition having the highest likelihood of reducing smoking. Teens in the N-O-T+FIT condition who increased the number of days on which they received at least 30 minutes of exercise were significantly more likely than those in other groups to quit smoking.

CONCLUSION

Findings suggest that it is possible to alter simultaneously more than one health behavior among teens-favorable changes in physical activity and smoking cessation may be particularly compatible targets for dual behavior change.

A history of ashes: an 80 year comparative portrait of smoking initiation in American Indians and Non-Hispanic whites--the Strong Heart Study

The consequences of starting smoking by age 18 are significant. Early smoking initiation is associated with higher tobacco dependence, increased difficulty in smoking cessation and more negative health outcomes. The purpose of this study is to examine how closely smoking initiation in a well-defined population of American Indians (AI) resembles a group of Non-Hispanic white (NHW) populations born over an 80 year period. We obtained data on age of smoking initiation among 7,073 AIs who were members of 13 tribes in Arizona, Oklahoma and North and South Dakota from the 1988 Strong Heart Study (SHS) and the 2001 Strong Heart Family Study (SHFS) and 19,747 NHW participants in the 2003 National Health Interview Survey. The participants were born as early as 1904 and as late as 1985. We classified participants according to birth cohort by decade, sex, and for AIs, according to location. We estimated the cumulative incidence of smoking initiation by age 18 in each sex and birth cohort group in both AIs and NHWs and used Cox regression to estimate hazard ratios for the association of birth cohort, sex and region with the age at smoking initiation. We found that the cumulative incidence of smoking initiation by age 18 was higher in males than females in all SHS regions and in NHWs (p < 0.001). Our results show regional variation of age of initiation significant in the SHS (p < 0.001). Our data showed that not all AIs (in this sample) showed similar trends toward increased earlier smoking. For instance, Oklahoma SHS male participants born in the 1980s initiated smoking before age 18 less often than those born before 1920 by a ratio of 0.7. The results showed significant variation in age of initiation across sex, birth cohort, and location. Our preliminary analyses suggest that AI smoking trends are not uniform across region or gender but are likely shaped by local context. If tobacco prevention and control programs depend in part on addressing the origin of AI smoking it may be helpful to increase the awareness in regional differences.

Does physician continuity within a clinical trial increase retention and compliance among adolescent smokers?

BACKGROUND

Retention and compliance are hurdles in many clinical trials designed for adolescents. Factors that may improve these issues in a challenging population may lead to increased data and power in much needed adolescent substance abuse research.

METHODS

Within a large-scale smoking cessation study for adolescents, physician continuity (PC) was examined to determine its effect on retention, compliance, and cessation.

RESULTS

In an analysis of 98 participants, participants with physician continuity throughout the study were more likely to attend more treatment visits and be medication compliant. It was also found that PC had no effect on participant smoking cessation.

CONCLUSIONS

It appears that PC may be one way to increase retention and compliance within an adolescent clinical trial, without interfering with the specific aim of the research study (in this case, smoking cessation).

Smoking cessation with teenagers: the relationship between impulsivity, emotional problems, program retention and effectiveness

AIMS

This study examines whether individual differences in impulsivity and emotional problems in adolescent smokers are related to initial smoking characteristics of participants, acceptance, retention and outcome of a school-based smoking cessation program.

DESIGN

The data was obtained from a feasibility study of a youth-specific, cognitive-behavioral and motivation enhancing program at 22 schools with 139 participating teenage smokers in Germany. A one-group-pre-posttest design was realized.

MEASUREMENT

Impulsivity levels were assessed by use of the impulsivity scale of the IVE ("Inventar zur Erfassung von Impulsivität, Risikoverhalten und Empathie", Stadler, Janke, & Schmeck, 2004). To evaluate the extent of emotional problems, the corresponding 5-items scale of the SDQ-Deu ("Strength and difficulties questionnaire", Klasen et al., 2000) was applied. Smoking behavior and acceptance of the program were assessed by students' self-reports.

FINDINGS

Acceptance and retention did not differ with regard to impulsivity and emotional problems, but initial smoking status did. Cessation rates varied with level of impulsivity: compared to non-impulsive participants, impulsive adolescents succeeded in quitting smoking less often. Emotional problems were not related to the rate of quitting.

CONCLUSIONS

Impulsive adolescents were similarly compliant to the offered cessation intervention as less impulsive smokers. In spite of their general positive evaluation, impulsive adolescents seem to benefit less from a smoking cessation program than their non-impulsive counterparts. Specific elements supporting impulsive teenage smokers in their goal to quit should be incorporated into youth-specific cessation programs.

Gender influences in tobacco use and cessation interventions

Smoking rates among and between men and women are in large part a reflection of the influence of gender and its intersections with other social factors including ethnicity, age, and social class that influence tobacco use and, ultimately, tobacco reduction and cessation. In this article, opportunities for developing and delivering gender-sensitive (programs addressing gender) and gender-specific (programs designed for men or women) interventions in the context of tobacco dependence treatment are discussed.

Effects of physical activity on teen smoking cessation

OBJECTIVE

To understand the influence of physical activity on teen smoking-cessation outcomes.

METHODS

Teens (N = 233; 14-19 years of age) from West Virginia high schools who smoked >1 cigarette in the previous 30 days were included. High schools with >300 students were selected randomly and assigned to brief intervention (BI), Not on Tobacco (N-O-T) (a proven teen cessation program), or N-O-T plus a physical activity module (N-O-T+FIT). Quit rates were determined 3 and 6 months after baseline by using self-classified and 7-day point prevalence quit rates, and carbon monoxide validation was obtained at the 3-month follow-up evaluation.

RESULTS

Trends for observed and imputed self-classified and 7-day point prevalence rates indicated that teens in the N-O-T+FIT group had significantly higher cessation rates compared with those in the N-O-T and BI groups. Effect sizes were large. Overall, girls quit more successfully with N-O-T compared with BI (relative risk [RR]: >∞) 3 months after baseline, and boys responded better to N-O-T+FIT than to BI (RR: 2-3) or to N-O-T (RR: 1-2). Youths in the N-O-T+FIT group, compared with those in the N-O-T group, had greater likelihood of cessation (RR: 1.48) at 6 months. The control group included an unusually large proportion of participants in the precontemplation stage at enrollment, but there were no significant differences in outcomes between BI and N-O-T (z = 0.94; P = .17) or N-O-T+FIT (z = 1.12; P = .13) participants in the precontemplation stage.

CONCLUSIONS

Adding physical activity to N-O-T may enhance cessation success, particularly among boys.

Effectiveness of intervention on improvement of drug use among methadone maintained adults

The purpose of this study is to evaluate the effectiveness of three interventions (individual motivational interviewing, group motivational interviewing, or nurse-led hepatitis health promotion) in reducing drug use. A randomized, controlled trial was conducted with 256 methadone maintained moderate-to-heavy alcohol-using adults attending one of five MM outpatient clinics. Drug use in the overall sample was significantly reduced from baseline to 6-month follow-up, as assessed by a 30-day recall (p < 0.0001), with a trend apparent for 6-month recall (p = 0.09). The group and individual programs revealed significant decreases in drug use at the 30-day recall.

Social cognitive mediators of adolescent smoking cessation: results from a large randomized intervention trial

Only one prior study has examined why adolescent smoking cessation interventions are effective. To address this understudied and important issue, we examined whether a large adolescent smoking cessation intervention trial's outcomes were mediated by social cognitive theory processes. In a randomized trial (N = 2,151), counselors proactively delivered a telephone intervention to senior year high school smokers. Mediators and smoking status were self-reported at 12-months postintervention eligibility (88.8% retention). At least 6-months abstinence was the outcome. Among all enrolled smokers, increased self-efficacy to resist smoking in (a) social and (b) stressful situations together statistically mediated 55.6% of the intervention's effect on smoking cessation (p < .001). Among baseline daily smokers, increased self-efficacy to resist smoking in stressful situations statistically mediated 56.9% of the intervention's effect (p < .001). Self-efficacy to resist smoking is a possible mediator of the intervention's effect on smoking cessation.