Do more graphic and aversive cigarette health warning labels affect Brazilian smokers' likelihood of quitting?

Between 2008 and 2013, Brazil experienced a large decline in smoking prevalence, with an innovative round of aversive pictorial health warnings implemented on cigarette packs and at points of sale in 2009. The objective of this study was to examine changes over time in the distribution of quitting attempts and self-reported thoughts about quitting due to health warnings among current smokers. We conducted a pre-post study to evaluate data from two nationally-representative surveys conducted in 2008 and 2013. Responses to questions on smokers' quitting attempts in the last year (yes vs. no) and whether health warnings led them to think about quitting in the last month (yes vs. no) were combined into four categories, for which the distribution of the Brazilian smoking population by year was estimated. A multinomial model was used to obtain proportions for each category, adjusted by socio-demographic variables and nicotine dependence. The proportion of smokers who reported making a quitting attempt in the last year and stated that health warnings led them think about quitting smoking statistically increased over time (from 30.0% to 33.1%; p-value = 0.010). The percentage of those who answered "no" to these two questions also increased over time (from 23.5% to 32.9%; p-value 0.001). These findings suggest that innovative warnings introduced in Brazil likely served as a "reminder" for continuing to think about cessation among those who attempted to quit in the last year. These warnings may have also triggered more avoidance of thinking about their contents than the previous warnings, which some studies have found to promote subsequent quitting activity. (C) 2016 Elsevier Ltd. All rights reserved.