Hutchinson Smoking Prevention Project: long-term randomized trial in school-based tobacco use prevention--results on smoking.

BACKGROUND: No long-term impact has yet been observed with the use of the social-influences approach to school-based smoking prevention for youth. However, whether this lack of impact is due to methodologic problems with the studies or to the failure of the interventions is unclear. The Hutchinson Smoking Prevention Project (HSPP), conducted from September 1984 through August 1999, aimed to attain the most rigorous randomized trial possible to determine the long-term impact of a theory-based, social-influences, grade 3-12 intervention on smoking prevalence among youth. METHODS: Forty Washington school districts were randomly assigned to the intervention or to the control condition. Study participants were children enrolled in two consecutive 3rd grades in the 40 districts (n = 8388); they were followed to 2 years after high school. The trial achieved high implementation fidelity and 94% follow-up. Data were analyzed with the use of group-permutation methods, and all statistical tests were two-sided. RESULTS: No significant difference in prevalence of daily smoking was found between students in the control and experimental districts, either at grade 12 (difference [Delta] = 0.2%, 95% confidence interval [CI] = -4.6% to 4.4%, and P =.91 for girls; Delta = 0.3%, 95% CI = -5.0% to 5.5%, and P =.89 for boys) or at 2 years after high school (Delta = -1.4%, 95% CI = -5.0% to 1.6%, and P =.38 for girls; Delta = 2.6%, 95% CI = -2.5% to 7.7%, and P =.30 for boys). Moreover, no intervention impact was observed for other smoking outcomes, such as extent of current smoking or cumulative amount smoked, or in subgroups that differ in a priori specified variables, such as family risk for smoking. CONCLUSION: The rigor of the HSPP trial suggests high credence for the intervention impact results. Consistent with previous trials, there is no evidence from this trial that a school-based social-influences approach is effective in the long-term deterrence of smoking among youth.

Initiation and use of smokeless tobacco in relation to smoking.

Questionnaire data obtained from 1,631 tenth grade students in 14 school districts in the State of Washington are used in this investigation of the relationship between the onset processes for smokeless tobacco use and smoking. Emphasized is the use of time-to-event data on the ages of occurrence of six events in these onset processes. Concepts and methods for the statistical analysis of time-to-event data are demonstrated. The occurrence of events in the smoking onset process are strongly related to increases in the subsequent onset rate for smokeless tobacco use. Compared with before initial smoking has occurred, the onset rates for weekly smokeless tobacco use after initial smoking has occurred are 2.03 (P less than .001) and 6.72 (P less than .001) times as large for males and females, respectively. Furthermore, both initial and weekly use of cigarettes contributes to the risk of subsequent weekly smokeless tobacco use. Conversely, the steps in the onset process of smokeless tobacco use are strongly related to increases in the subsequent smoking onset rate. Possible implications for intervention in prevention of smokeless tobacco use and for further research are discussed.

Experimental design and methods for school-based randomized trials. Experience from the Hutchinson Smoking Prevention Project (HSPP).

Nonadherence to accepted design principles for randomized trials has been a limitation of school-based intervention research. Designed to overcome these limitations, the Hutchinson Smoking Prevention Project (HSPP) is a 15-year randomized trial to determine the extent to which a school-based (grades 3-12) tobacco use prevention intervention can deter youth tobacco use throughout and beyond high school. This paper presents the HSPP experimental design, together with methods for its implementation, and an evaluation of the degree to which HSPP has adhered to principles of randomized trials. Results from the experimental design and its conduct include (1) a recruitment rate of 97.6% (40 of 41 targeted school districts), (2) full and active participation for the trial's duration by 100% of the 40 school districts recruited, (3) implementation by virtually all teachers (99%+), with 86% implementation fidelity, and (4) outcome determination for 94.3% (7910) of 8388 original study participants identified 12 years previously at baseline. The high degree of rigor achieved by the HSPP experimental design ensures confidence in the trial's soon-to-be available intervention effectiveness results. Equally important, for future school-based trials, the HSPP design and its execution have illustrated that school-based research can adhere to the principles of rigorous randomized trials, with high rates of implementation, and very high rates of recruitment, maintenance, and follow-up of study participants, even for studies with decade-long follow-up periods. Rigor in school-based trials can be achieved through a combination of (1) commitment to the principles of randomized trials, (2) attention to the special challenges of trials specific to the school setting, (3) adoption and meticulous execution of proven methods for trial conduct, and (4) establishment at the outset of principles for maintaining positive collaborative relationships with participating school districts for the duration of the trial. These findings are important in light of the great potential for using the nation's schools to access youth for health promotion/risk-factor prevention.

The Hutchinson Smoking Prevention Project trial: design and baseline characteristics.

INTRODUCTION: This paper describes the experimental design and baseline characteristics of the Hutchinson Smoking Prevention Project (HSPP), a 15-year trial to determine to what extent a grade 3-12 school-based tobacco use prevention intervention can deter tobacco use throughout and beyond high school. DESIGN: Trial design features include use of the school district as the unit of randomization, inclusion of the school district's entire enrollment of 3rd graders, long-term follow-up of the entire original cohort, and sample size and evaluation methods that account for the group-randomization and intraclass correlation of endpoints within school districts. The theory-based intervention is teacher-led and includes grade 3-10 curriculum units, teacher training, grade 9-12 tobacco use cessation materials, and high school staff newsletters. RESULTS: Baseline data were collected on the trial cohort of 8388 children and their parents and on the 40 collaborating school districts and communities. A comparison of the distribution of baseline variables between experimental conditions shows good balance. CONCLUSIONS. The HSPP trial's experimental design will provide a rigorous test of the intervention. The balance in baseline variables between the experimental and control conditions will help provide assurance that the trial's intervention effectiveness results, scheduled for publication in 2000, will be unbiased.