Changes in adult cigarette smoking prevalence after 5 years of community health education: the Stanford Five-City Project.

To determine the effects of 5 years of community-wide cardiovascular health education on smoking prevalence and cessation, the authors analyzed data from the Stanford Five-City Project, an experimental field study with two treatment cities and two control cities. Representative samples of the population aged 12-74 years were drawn at baseline and every 2 years thereafter to obtain four independent cross-sectional surveys; participants aged 25-74 years are included in this paper (n approximately 440 per city per survey; total n = 6,981). The baseline sample was asked to return to three follow-up surveys, also 2 years apart, and those that did (n = 805) constitute the cohort survey sample. Self-reported cigarette smoking was confirmed by plasma thiocyanate and expired-air carbon monoxide levels. Smoking prevalence decreased over time in all cities, but in the cohort the decrease tended to be greater in treatment than in control cities (p = 0.10, two-tailed); the treatment-control difference was consistent over time (-1.51 percentage points/year in treatment vs. -0.78 percentage points/year in control, p = 0.007, two-tailed). In contrast, smoking prevalence in the independent samples declined similarly in treatment and control cities, changes were not linear, and rates varied within cities between times. Baseline smokers in both the cohort and the follow-up independent surveys were significantly more likely to quit in the treatment cities than in the control cities.