Kade Patanavanich, Methavee Worawattanakul, and I just published “Longitudinal bidirectional association between youth electronic cigarette use and tobacco cigarette smoking initiation in Thailand” in Tobacco Control. This paper shows that in Thailand, as in richer countries, never-smoking youth who use e-cigarettes are more likely to become smokers than kids who don’t use e-cigarettes. (Kids who start with cigarettes are also more likely to add e-cigarettes.) The only difference between the risk we found and the average risks found in earlier studies done in rich countries is that the risk of going on to cigarettes we found in Thailand was higher. This may reflect the fact that our study was done at a time when the more addictive protonated e-cigs pioneered by Juul dominated the market whereas the earlier studies were mostly done when the market was dominated by older generation e-cigs.
This paper provides important evidence for Thai policy makers to maintain their ban on sales of electronic nicotine deliver devices (which include liquid e-cigs and solid heated tobacco products) despite industry pressure. Our new paper specifically debunks claims by e-cig advocates in Thailand that youth e-cig use does not increase cigarette smoking.
This is a longitudinal study where youth are followed forward in time, so there is not an issue of reverse causality, a criticism popular with e-cig advocates.
Here is the abstract:
Introduction: This study quantifies the longitudinal association between e-cigarette use and subsequent conventional cigarette initiation and vice versa among Thai youths.
Methods: Data from a longitudinal survey of 6045 Thai seventh grade students with baseline in 2019 and the 12-month follow-up in 2020 were analysed using complex survey multivariate logistic regressions to assess whether e-cigarette use was associated with subsequent cigarette smoking (ever, current and dual product users at follow-up) among baseline never smokers.
Results: Consistent with prior findings from other countries, among those who had never smoked cigarettes at baseline, ever e-cigarette users were more likely to try cigarette smoking (adjusted OR 4.44; 95% CI 2.23 to 8.86; p<0.001), or become dual users (adjusted OR 5.31; 95% CI 2.63 to 10.74; p<0.001) 1 year later. Baseline current e-cigarette users were more likely to become ever smokers (adjusted OR 5.37; 95% CI 1.82 to 15.90; p=0.005), current smokers (OR 3.92; 95% CI 1.69 to 9.14; p=0.003) and dual product users (adjusted OR 6.96; 95% CI 1.54 to 31.38; p=0.015) at the 12-month follow-up than non-e-cigarette users. Similarly, among never e-cigarette users at baseline, ever cigarette smoking were more likely to try e-cigarettes (adjusted OR 3.38; 95% CI 1.66 to 6.88; p=0.002), currently use e-cigarettes (adjusted OR 2.75; 95% CI 1.47 to 5.13; p=0.003) and currently use both e-cigarettes and cigarettes (adjusted OR 4.87; 95% CI 2.92 to 8.13; p<0.001) at the follow-up than never smokers. Among never e-cigarette users at baseline, current-cigarette smoking were more likely to try e-cigarettes (adjusted OR 6.21; 95% CI 2.58 to 14.95; p<0.001), currently use e-cigarettes (adjusted OR 2.80; 95% CI 1.27 to 6.14; p=0.014) and currently use both e-cigarettes and cigarettes (adjusted OR 7.70; 95% CI 3.45 to 17.19; p<0.001) at the follow-up than never smokers.
Conclusions: This longitudinal study in Asian low-income and middle-income countries supports the prospective association of youth e-cigarette use with subsequent smoking initiation and youth cigarette use with subsequent e-cigarette initiation that is similar to that observed in high-income Western countries.
The full citation is: Patanavanich R, Worawattanakul M, Glantz S. Longitudinal bidirectional association between youth electronic cigarette use and tobacco cigarette smoking initiation in Thailand. Tob Control. 2022 Sep 14:tobaccocontrol-2022-057491. doi: 10.1136/tc-2022-057491. Epub ahead of print. PMID: 36104174. It is available here.