The effect of graphic cigarette warning labels on smoking behavior: evidence from the Canadian experience.

INTRODUCTION: There is a substantial literature that graphic tobacco warnings are effective; however, there is limited evidence based on actual smoking behavior. The objective of this paper is to assess the effect of graphic cigarette warning labels on smoking prevalence and quit attempts.
METHODS: A nationally representative sample of individuals aged 15 years and older from the Canadian National Population Health Survey 1998-2008 is used. The sample consists of 4,853 individuals for the smoking prevalence regression and 1,549 smokers for quit attempts. The generalized estimating equation (GEE) model was used to examine the population-averaged (marginal) effects of tobacco graphic warnings on smoking prevalence and quit attempts. To assess the effect of graphic tobacco health warnings on smoking behavior, we used a scaled variable that takes the value of 0 for the first 6 months in 2001, then increases gradually to 1 from December 2001.
RESULTS: We found that graphic warnings had a statistically significant effect on smoking prevalence and quit attempts. In particular, the warnings decreased the odds of being a smoker (odds ratio [OR] = 0.875; 95% CI = 0.821-0.932) and increased the odds of making a quit attempt (OR = 1.330, CI = 1.187-1.490). Similar results were obtained when we allowed for more time for the warnings to appear in retail outlets.
CONCLUSION: This study adds to the growing body of evidence on the effectiveness of graphic warnings. Our findings suggest that warnings had a significant effect on smoking prevalence and quit attempts in Canada.