Community intervention trial for smoking cessation (COMMIT): II. Changes in adult cigarette smoking prevalence.

OBJECTIVES: COMMIT (Community Intervention Trial for Smoking Cessation) investigated whether a community-level multichannel intervention would decrease the prevalence of adult cigarette smoking and increase quitting, with heavy smokers (> or = 25 cigarettes per day) receiving the highest priority. METHODS: One community within each of 11 matched community pairs (10 in the United States, 1 in Canada) was randomly assigned to intervention. Baseline (1988) and final (1993) telephone surveys sampled households to determine prevalence of smoking behavior. RESULTS: Among the target population aged 25 to 64 years, there was no intervention effect on heavy smoking prevalence, which decreased by 2.9 percentage points in both intervention and comparison communities. Overall smoking prevalence decreased by 3.5 in intervention communities vs 3.2 in comparison communities, a difference not statistically significant, while the mean quit ratios were 0.198 versus 0.185, respectively, a difference of 0.013 (90% test-based confidence interval = -0.003, 0.028). CONCLUSIONS: Results are consistent with the cohort analysis reported separately, although the more powerful cohort design showed a statistically significant intervention effect upon light-to-moderate smokers. This community-based intervention did not have a significant impact on smoking prevalence beyond the favorable secular trends. In future efforts, additional strategies should be incorporated and rigorously evaluated.