Efficacy of e-cigarettes for smoking cessation in populations with psychiatric and/or substance use problems: A secondary analysis of a randomized controlled trial

INTRODUCTION People with psychiatric and substance use disorders are more likely to smoke and less likely to quit than smokers in the general population. We evaluated the efficacy of e-cigarettes for abstinence from tobacco smoking in people with psychiatric and substance use problems. METHODS We analyzed data collected in the larger 'Efficacy, Safety, and Toxicology of ENDS as an Aid for Smoking Cessation' (ESTxENDS) trial (n=1246): the intervention group received e-cigarettes and e-liquids, plus standard-of-care smoking cessation counseling (SOC) for 6 months; the control group received SOC and a voucher. The primary outcome was biochemically validated continuous self-reported abstinence at 6 months; secondary outcomes included 6-month and 7-day self-reported abstinence. We calculated adjusted relative risks (ARR) for two subsamples meeting these conditions at the baseline visit: 1) psychotropic medication use; and 2) problematic substance or polysubstance use. RESULTS Among the participants using psychotropic medications (n=239), the ARR for validated abstinence was 2.62 (95% CI: 1.40-4.90) in the intervention group versus the control group, 2.95 (95% CI: 1.72-5.07) for 6-month and 2.96 (95% CI: 1.92-4.55) for 7-day self-reported abstinence, while among participants with problematic substance or polysubstance use (n=818), the ARR was 1.57 (95% CI: 1.20-2.04), 1.42 (95% CI: 1.15-1.74), and 1.53 (95% CI: 1.31-1.79), respectively. CONCLUSIONS Adding e-cigarettes to standard-of-care counseling increased the likelihood that participants with psychiatric and substance use problems would abstain from smoking, but larger studies should test the efficacy and safety of