Cigarette packet warning labels can prevent relapse: findings from the International Tobacco Control 4-Country policy evaluation cohort study

OBJECTIVES: To investigate the links between health warning labels (WLs) on cigarette packets and relapse among recently quit smokers. DESIGN: Prospective longitudinal cohort survey. SETTING: Australia, Canada, the UK and the USA. PARTICIPANTS: 1936 recent ex-smokers (44.4% male) from one of the first six waves (2002-2007) of the International Tobacco Control 4-Country policy evaluation survey, who were followed up in the next wave. MAIN OUTCOME MEASURES: Whether participants had relapsed at follow-up (approximately 1 year later). RESULTS: In multivariate analysis, very frequent noticing of WLs among ex-smokers was associated with greater relapse 1 year later (OR: 1.52, 95% CI 1.11 to 2.09, p<0.01), but this effect disappeared after controlling for urges to smoke and self-efficacy (OR: 1.29, 95% CI 0.92 to 1.80, p=0.135). In contrast, reporting that WLs make staying quit 'a lot' more likely (compared with 'not at all' likely) was associated with a lower likelihood of relapse 1 year later (OR: 0.65, 95% CI 0.49 to 0.86, p<0.01) and this effect remained robust across all models tested, increasing in some. CONCLUSIONS: This study provides the first longitudinal evidence that health warnings can help ex-smokers stay quit. Once the authors control for greater exposure to cigarettes, which is understandably predictive of relapse, WL effects are positive. However, it may be that ex-smokers need to actively use the health consequences that WLs highlight to remind them of their reasons for quitting, rather than it being something that happens automatically. Ex-smokers should be encouraged to use pack warnings to counter urges to resume smoking. Novel warnings may be more likely to facilitate this.