The Hutchinson Smoking Prevention Project trial: design and baseline characteristics

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.

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.

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.