Dr Shahab is Professor of Health Psychology at University College London and past President for the Society for Research on Nicotine and Tobacco – Europe. He trained in psychology, epidemiology and neuroscience and has more than 15 years’ experience in addiction research, tobacco control and health psychology. Dr Shahab’s expertise spans work on novel behavioural and pharmacological smoking cessation interventions, biomarkers, tobacco product regulation and policy, digital health and tobacco and alcohol use epidemiology. Dr Shahab has collaborated with academic as well as non-academic (e.g. governmental and non-governmental) partners and to date has authored over 120 scientific papers, reports and reviews in this area.
Disentangling the youth gateway of e-cigarettes: findings from three different data sources
There is disagreement in the literature as to whether e-cigarettes are a gateway to traditional cigarette smoking among adolescents, or whether e-cigarettes displace smoking. Observable data (e.g. from the United States) find a strong displacement effect but many published studies suggest that e-cigarettes act as a gateway to cigarette use by documenting a positive association between e-cigarette use initiation and subsequent cigarette use. Yet, these associations may not be causal and instead due to a confounding factor (i.e. an omitted variable or common liability) that determines both e-cigarette use and subsequent cigarette use. This presentation will try to address this problem of confounding, using a three-pronged approach: smoking rates among adolescents with initial e-cigarette use will be compared with 1) a real-world control group (adolescents with initial non-combustible, non-cigarette tobacco use), 2) a synthetic control group, selected using propensity score matching (PSM) and 3) associations of changes in youth e-cigarette use and smoking uptake at population level will be assessed using timeseries analysis. Data for the first two analyses come from the National Youth Tobacco Survey (2014-2015, N=37,417, age 9-18) and the first three waves of the PATH study (2013-2016, N=5,544, age 12-17) and for the third analysis from the Smoking Toolkit Study (STS) (2008-2018, N=37,105, age 16-24). Results highlight that the impact of e-cigarette use on subsequent smoking is complex and may depend on underlying sample characteristics but that the net effect of e-cigarettes on smoking uptake appears to be negligible at population level.