Objective To compare two methods to estimate the magnitude of the illicit cigarette trade in Mexico and to contrast these results with tobacco industry figures.

Methods We used two survey methods: a smoker survey and a discarded pack survey. Data were collected in eight major cities in Mexico between November and December 2017. A total of 2396 face-to-face interviews to adult smokers were conducted and 8204 discarded packs were collected. To determine whether cigarette packs were intended for the Mexican market, we analysed pack features required by Mexican regulations and self-reported brands of the last purchase. Standard statistical tests to compare proportions were employed. Correlates of illicit cigarette use were also analysed.

Results The share of cigarettes not intended for the Mexican market was 8.8% based on the analysis of discarded packs and 7.6% based on the survey of smokers, that is, the difference was small and only borderline significant overall (p=0.055). Also, both results were lower than those presented by the tobacco industry (16.6%). However, differences across methods were statistically significant for various cities.

Conclusion Our results suggest that the optimal practice for the study of illicit trade is to cross validate estimates using both the smoker survey and the littered pack survey. If resources are limited, however, our findings indicate that either method could be used because both yield similar overall results, as longs as the potential biases are considered. Also, consistent with findings from other studies, our results suggest that the tobacco industry exaggerates the scope of illicit cigarette trade.