Building on the important work of earlier adolescent smoking cessation studies, the HS intervention addressed barriers to intervention reach and effectiveness. The trial successfully recruited more than 65% of targeted smokers in a general population of adolescents compared with the 2%–10% of smokers who are typically recruited to school-based smoking cessation programs (5
). The HS intervention was implemented via telephone by trained counselors, with fidelity to core principles of MI and adherence to the MI plus CBST treatment protocol, and yielded statistically significant increases in smoking abstinence at 12 months postintervention eligibility (1
This trial's positive results from an intervention with a major MI component contribute to the field of MI intervention research. At the time this intervention was being developed, studies of MI in brief telephone counseling for smoking cessation had been tested successfully with both contemplative and precontemplative adults (70
) and showed promise for use with adolescents (64
). Since then, results of studies of MI for adolescent and young adult smoking cessation have been mixed: In a trial of 85 non–treatment-seeking adolescent daily smokers, Colby et al. (73
) reported statistically significant increases in 7-day abstinence at 6-month follow-up with one session of MI compared with standard brief advice. However, three other adolescent cessation trials (74
) and one trial of young adult smokers (77
) testing MI reported no statistically significant differences in cessation rates. Prokhorov et al. (78
) tested MI with expert system-generated feedback against standard advice in a randomized trial of 426 daily-smoking college students; higher 7-day quit rates at 10-month follow-up were suggestive of a treatment effect (P
= .068). Hollis et al. (79
) also tested an expert system consisting of behavioral counseling that incorporated MI in a trial of 2526 adolescents (589 smokers) and observed statistically significantly higher 30-day abstinence rates at the 1- and 2-year follow-ups in the intervention arm. Results of a large randomized trial by the California Smokers’ Helpline, comparing telephone counseling that integrated MI and cognitive behavioral therapy with written materials vs written materials alone, showed that statistically significantly more clients in the telephone counseling group than in the control group quit and remained abstinent for 6 months (80
). More recently, Pbert et al. (81
) reported statistically significant 6-month treatment effects for 30-day abstinence in their trial of 2711 adolescent smokers and nonsmokers who received a smoking prevention or cessation intervention based on the 5A model that incorporated MI and cognitive behavioral therapy compared with those who received usual pediatric care. Now the HS trial has reported statistically significant treatment effects for multiple abstinence outcomes, including 6-month prolonged abstinence among baseline daily smokers (P
= .02) (1
). This trial's results, combined with the long-term results of the trials by Pbert et al. (81
) and Hollis et al. (79
), support the effectiveness of adolescent smoking cessation incorporating MI.
That the telephone counseling was delivered with fidelity to MI core elements enhances the internal validity of the intervention. Few studies of MI report evaluations of treatment fidelity (83
). One possible reason may be that most MI interventions evaluated to date have tested MI in combination with other treatment modalities, for example, providing problem feedback or skills training (83
). When the integrity of such interventions is examined, limited resources may preclude evaluation of all components. It is often the component considered most central to the intervention, such as the 5A model as described in Pbert et al. (82
), that is assessed, rather than the core elements of MI (67
). Unfortunately, without evaluations of adherence to MI, accurate conclusions cannot be drawn regarding the efficacy of MI interventions nor can their contributions to behavior change be fully understood.
For reasons beyond those established at the outset of the trial, including the nonsmoker intervention proved valuable. The irregular smoking patterns of adolescent smokers (5
) and their proclivity for spontaneously starting and stopping smoking is well documented (eg, 84). Perhaps because of these characteristics, and the 9-month lapsed time between the trial's baseline survey and intervention contact, 36% of the baseline smokers subsequently reported at their initial counseling call that they currently did not smoke and had not smoked in the past 6 months. Possible explanations for the change in reported status include that participants had 1) accurately reported quitting since their baseline survey; 2) not reported their smoking status accurately, either to the counselors or on their baseline survey; or 3) smoked but because of the infrequency of their smoking did not consider themselves to be smokers. Regardless of the cause for the discrepancy, it proved important that there was a nonsmoker intervention available for these baseline smokers turned nonsmokers. For this reason, and because including nonsmokers in the intervention can help prevent stigmatization of smokers, researchers should consider the potential benefits of including a nonsmoker component when developing adolescent smoking cessation interventions.
Limitations specific to intervention design and implementation include counselor failure to initially contact 97 (10.2%) of the 948 eligible smokers, failure to recontact and initiate telephone counseling with 34 (3.6%) consented smokers, and failure to recontact 169 (17.8%) participating smokers for some of their scheduled calls. Further efforts are needed to continue to improve methods for contacting, engaging, and keeping adolescents in effective interventions. Another possible limitation is the 9-month gap, because of study design, between determination of the adolescents’ baseline smoking status and start of their intervention, during which time changes in adolescents’ smoking status occurred. Finally, that counselors did not achieve benchmark quality scores on two of six core behaviors of MI may limit somewhat our conclusions about MI fidelity.
Many of the approaches used successfully in this trial may be transferable to other interventions for young people and to other settings. For example, the methods for collection of active parental consent can be applied widely to other interventions involving minors. The proactive identification and recruitment of adolescents within a specific population, used with schools in this trial, can be applied in other settings as well: Both Hollis et al. (79
) and Pbert et al. (81
) proactively identified and recruited teen smokers and nonsmokers in health-care settings. Proactive telephone counseling and use of MI plus skills training, used in the HS intervention, can be used in other settings and for other behavior change applications. Evaluations of such use are strongly encouraged.
It will be important to follow up these promising results with additional research. First, it is essential to replicate the results of this intervention in other populations and settings and to evaluate modifications that could strengthen the intervention, both for reach and for effectiveness. Second, learning whether MI and CBST counseling processes predict smoking cessation outcomes would also be scientifically useful. Third, intervention modifications should be studied that would facilitate wide dissemination, for example, evaluation of a more limited counselor training protocol with both professional and lay counselors and evaluation of additional methods for proactively identifying smokers for cessation counseling. Similarly, before the HS intervention is considered for use with adolescents by existing tobacco quitlines, evaluation of the MI plus CBST telephone counseling component in a reactive quitline setting may be useful. Because counselor behavior that is consistent with MI has been shown to be positively associated with therapeutic alliance and treatment engagement (85
), another possible future area of investigation is examination of effect of counselor behavior on intervention recruitment and retention.
Experience with the HS intervention demonstrates that telephone-based smoking cessation interventions that address research-identified challenges and barriers can be developed and successfully implemented with adolescent smokers. Moreover, proactive implementation of such interventions can extend intervention reach and achieve statistically significant rates of smoking abstinence in a large general population of adolescent smokers, thus contributing to national public health goals to reduce smoking among the US population of adolescents and young adults.