Counterfactual Trend Modeling to Examine How Youth Smoking Trends Changed during the E-Cigarette Era

Poster #159

Authors: Selya A, Foxon F

Abstract: A major concern about e-cigarettes is that they may act as a gateway to cigarette smoking – the most harmful tobacco product – among youth; however, while there is clearly an association between e-cigarette use and smoking among youth, growing evidence supports that the association is not causal but rather is an indicator of heightened pre-existing risk for cigarette smoking. Because the gateway hypothesis would predict more cigarette smokers with increasing e-cigarette use than would otherwise be expected, population-level trends are an important data source that can provide additional supporting or opposing evidence for the gateway hypothesis. This presentation presents an updated simulation modeling analysis calibrated to NYTS data, which examines different hypotheses about e-cigarettes’ effects on cigarette smoking. The model simulates youth smoking prevalence through 2022 under the following scenarios: 1) “counterfactual” smoking prevalence, i.e. if pre-e-cigarette (i.e. before 2010) smoking trends had continued; 2) a “gateway” scenario in which e-cigarette use acted as a gateway to cigarettes for 25% of e-cigarette users per year ; 3) a “diversion” scenario in which 25% of e-cigarette users per year are diverted from ever initiating smoking; and 4) a combined scenario in which both gateway and diversion scenarios are active simultaneously. Actual cigarette smoking trends are lower than would be expected from the counterfactual projections. Actual cigarette smoking trends are inconsistent with a gateway effect of any degree; in fact, a strong diversion effect (greater than the initially-tested 25%) is necessary to explain observed declines in smoking prevalence. While it is possible that a gateway effect could be occurring for a minority of youth, an even stronger “diversion” effect (>65% of e-cigarette users per year) is necessary to explain actual NYTS smoking trends. This presentation also reviews other similar population-trend modeling studies that examine the gateway question. It is possible that e-cigarettes are a gateway for a small minority of youth, but on net, e-cigarettes appear to be diverting youth in larger numbers away from more harmful cigarette smoking.

Disclosures: Through PinneyAssociates, Inc. authors AS and FF provide consulting services on tobacco harm reduction to Juul Labs, Inc. Juul Labs had no role in the analyses presented here but are supporting presentation of them.