Estimating the Effects of Vaping Frequency on Smoking Cessation Using PATH Study Data: A Causal Forest Approach

Introduction: E-cigarettes are the second most commonly used nicotine product in the United States after cigarettes. Their role in smoking cessation remains debated. Further research is needed to clarify their potential impact on quitting combustible cigarette use. Methods: We analyzed data from adults aged 18 and older who participated in Wave 4 (12/2016-01/2018), Wave 5 (12/2018-11/2019), and Wave 7 (01/2022-04/2023) of the Population Assessment of Tobacco and Health Study. We employed a causal forest to estimate the associations between Wave 5 e-cigarette use and past 12-month cigarette smoking abstinence at Wave 7. Eligible participants had smoked at least 100 cigarettes in their lifetime at Wave 4, currently smoked cigarettes some days or every day at both Waves 4 and 5, completed follow-up at Wave 7, and had a substantial estimated probability of either vaping or not vaping at Wave 5. Analyses adjusted for 26 Wave 4 covariates, including demographic characteristics, tobacco use history, and other relevant factors. Results: Compared with no vaping, vaping on 1-5 days was associated with a 2.4 percentage-point lower probability of cessation (95% CI: -7.7 to 2.9), whereas vaping on 6-29 days and daily vaping were associated with increases of 7.5 percentage points (95% CI: -0.4 to 15.5) and 12.5 percentage points (95% CI: 6.2 to 18.7), respectively. Conclusions: The association between vaping and smoking cessation varied by vaping frequency. Compared with non-vaping, infrequent vaping was not significantly associated with subsequent cigarette abstinence, whereas more frequent vaping was associated with a greater likelihood of abstinence. Daily vaping showed the strongest positive association.